Solved [Solved] Unable to sell items when trading with NPCs

<?xml version="1.0" encoding="UTF-8"?>
<npc name="Eryn" nameDescription="Eryn, the rune vendor" script="runes.lua" walkinterval="2000" floorchange="0" skull="white">
    <health now="100" max="100"/>
    <look type="130" head="96" body="86" legs="0" feet="0" addons="1"/>
    <parameters>
        <parameter key="message_greet" value="Hello |PLAYERNAME|. I sell runes, potions, wands and rods... {trade} with me if you want. You can also receive your {first rod} or {first wand} from me."/>
        <parameter key="message_decline" value="Is |TOTALCOST| gold coins too much for you? Get out of here!"/>
        <parameter key="module_shop" value="1"/>
        <parameter key="message_farewall" value="Farewell, |PLAYERNAME|!"/>
        <parameter key="message_walkaway" value="You shall not walk away on me!"/>
        <parameter key="shop_sellable" value="empty small potion flask,7636,5;empty strong potion flask,7634,10;empty great potion flask,7635,15;wand of vortex,2190,250;wand of dragonbreath,2191,500;wand of decay,2188,2500;wand of draconia,8921,3750;wand of cosmic energy,2189,5000;wand of inferno,2187,7500;wand of starstorm,8920,9000;wand of voodoo,8922,11000;snakebite rod,2182,250;moonlight rod,2186,500;necrotic rod',2185,2500;northwind rod,8911,3750;terra rod,2181,5000;hailstorm rod,2183,7500;springsprout rod,8912,9000;underworld rod,8910,11000;"/>
        <parameter key="shop_buyable" value="spellbook,2175,150;magic lightwand,2163,400;small health potion,8704,20;health potion,7618,45;mana potion,7620,50;strong health potion,7588,100;strong mana potion,7589,80;great health potion,7591,190;great mana potion,7590,120;great spirit potion,8472,190;ultimate health potion,8473,310;antidote potion,8474,50;intense healing rune,2265,95;ultimate healing rune,2273,175;magic wall rune,2293,350;destroy field rune,2261,45;light magic missile rune,2287,40;heavy magic missile rune,2311,120;great fireball rune,2304,180;explosion rune,2313,250;sudden death rune,2268,350;death arrow rune,2263,300;paralyze rune,2278,700;animate dead rune,2316,375;convince creature rune,2290,80;chameleon rune,2291,210;desintegreate rune,2310,80;blank rune,2260,10;wand of vortex,2190,500;wand of dragonbreath,2191,1000;wand of decay,2188,5000;wand of draconia,8921,7500;wand of cosmic energy,2189,10000;wand of inferno,2187,15000;wand of starstorm,8920,18000;wand of voodoo,8922,22000;snakebite rod,2182,500;moonlight rod,2186,1000;necrotic rod',2185,5000;northwind rod,8911,7500;terra rod,2181,10000;hailstorm rod,2183,15000;springsprout rod,8912,18000;underworld rod,8910,22000;"/>
    </parameters>
</npc>

local keywordHandler = KeywordHandler:new()
local npcHandler = NpcHandler:new(keywordHandler)
NpcSystem.parseParameters(npcHandler)
local talkState = {}

function onCreatureAppear(cid)                npcHandler:onCreatureAppear(cid)            end
function onCreatureDisappear(cid)             npcHandler:onCreatureDisappear(cid)            end
function onCreatureSay(cid, type, msg)            npcHandler:onCreatureSay(cid, type, msg)        end
function onThink()                    npcHandler:onThink()                    end

local items = {[1] = 2190, [2] = 2182, [5] = 2190, [6] = 2182}
function creatureSayCallback(cid, type, msg)
    if(not npcHandler:isFocused(cid)) then
        return false
    end

    local talkUser = NPCHANDLER_CONVBEHAVIOR == CONVERSATION_DEFAULT and 0 or cid
    if(msgcontains(msg, 'first rod') or msgcontains(msg, 'first wand')) then
        if(isSorcerer(cid) or isDruid(cid)) then
            if(getPlayerStorageValue(cid, 30002) <= 0) then
                selfSay('So you ask me for a {' .. getItemNameById(items[getPlayerVocation(cid)]) .. '} to begin your advanture?', cid)
                talkState[talkUser] = 1
            else
                selfSay('What? I have already gave you one {' .. getItemNameById(items[getPlayerVocation(cid)]) .. '}!', cid)
            end
        else
            selfSay('Sorry, you aren\'t a druid either a sorcerer.', cid)
        end
    elseif(msgcontains(msg, 'yes')) then
        if(talkState[talkUser] == 1) then
            doPlayerAddItem(cid, items[getPlayerVocation(cid)], 1)
            selfSay('Here you are young adept, take care yourself.', cid)
            setPlayerStorageValue(cid, 30002, 1)
        end
        talkState[talkUser] = 0
    elseif(msgcontains(msg, 'no') and isInArray({1}, talkState[talkUser])) then
        selfSay('Ok then.', cid)
        talkState[talkUser] = 0
    end

    return true
end

npcHandler:setCallback(CALLBACK_MESSAGE_DEFAULT, creatureSayCallback)
npcHandler:addModule(FocusModule:new())

<?xml version="1.0" encoding="UTF-8"?>
<npc name="Marco" script="default.lua" walkinterval="4000" floorchange="0">
    <health now="150" max="150"/>
    <look type="143" head="97" body="77" legs="96" feet="97" addons="3"/>
    <parameters>
        <parameter key="message_greet" value="Hey |PLAYERNAME|... If you seek a sharp weapon, {trade} with me!"/>
        <parameter key="module_shop" value="1"/>
        <parameter key="message_farewall" value="Bye..."/>
        <parameter key="message_walkaway" value="Pfff!"/>
        <parameter key="shop_sellable" value="two handed sword,2377,335;dagger,2379,3;spike sword,2383,750;rapier,2384,30;sabre,2385,112;magic longsword,2390,300000;fire sword,2392,3000;giant sword,2393,12750;carlin sword,2395,750;ice rapier,2396,750;longsword,2397,37;silver dagger,2402,375;knife,2403,1;combat knife,2404,4;sickle,2405,7;short sword,2406,60;bright sword,2407,2250;warlord sword,2408,75000;serpent sword,2409,675;poison dagger,2411,37;katana,2412,30;broadsword,2413,262;golden sickle,2418,75;scimitar,2419,112;heavy machete,2442,67;epee,2438,75000;bone sword,2450,75;djinn blade,2451,450000;avenger,6528,150000;demonrage sword,7382,7500;relic sword,7383,18750;mystic blade,7384,7500;crimson sword,7385,375;mercenary sword,7386,15000;justice seeker,7390,52500;thaian sword,7391,11250;dragon slayer,7402,11250;assassin dagger,7404,11250;havoc blade,7405,5250;blacksteel sword,7406,1500;haunted blade,7407,7500;wyvern fang,7408,1500;bloody edge,7416,7500;runed sword,7417,7500;nightmare blade,7418,22500;crystal sword,7449,450;emerald sword,8930,225000;jagged sword,8602,60000;golden sword,8931,750000;calamity,8932,52500;war hammer,2391,675;morning star,2394,75;mace,2398,22;staff,2401,18;crowbar,2416,37;battle hammer,2417,112;thunder hammer,2421,225000;iron hammer,2422,37;clerical mace,2423,150;silver mace,2424,75000;dragon hammer,2434,1500;skull staff,2436,4500;daramanian mace,2439,150;hammer of wrath,2444,56000;crystal mace,2445,22500;studded club,2448,26;bone club,2449,37;arcane staff,2453,22500;lich staff,3961,11250;banana staff,3966,750;brutetamers staff,7379,1500;mammoth whopper,7381,300;diamond sceptre,7387,3000;orcish maul,7392,750;sapphire hammer,7437,5250;shadow sceptre,7451,75000;spiked squelcher,7452,375;queens sceptre,7410,1500000;abyss hammer,7414,375000;cranial basher,7415,7500;jade hammer,7422,52500;lunar staff,7424,5250;taurus mace,7425,450;amber staff,7426,6000;chaos mace,7427,7500;dragonbone staff,7430,2250;furry club,7432,375;dark trinity mace,8927,525000;obsidian truncheon,8928,300000;stomper,8929,187500;battle axe,2378,75;hand axe,2380,15;halberd,2381,300;double axe,2387,225;hatchet,2388,18;great axe,2415,15000;obsidian lance,2425,375;naginata,2426,750;guardian halberd,2427,2250;orcish axe,2428,150;barbarian axe,2429,225;knight axe,2430,750;stonecutter axe,2431,400000;fire axe,2432,5250;dwarven axe,2435,750;daramanian waraxe,2440,675;daramanian axe,2441,300;ravagers axe,2443,37500;twin axe,2447,40000;war axe,2454,7500;beastslayer axe,3962,1500;ruthless axe,6553,52500;headchopper,7380,3000;vile axe,7388,40000;heroic axe,7389,11250;relic axe,7411,30000;butchers axe,7412,52500;titan axe,7413,30000;bloodslayer axe,7453,30000;destroyers axe,7454,40000;ice double axe,7455,67500;cursed axe,7433,22500;royal axe,7434,112500;black axe,7435,225000;angelwing axe,7436,150000;"/>
        <parameter key="shop_buyable" value="two handed sword,2377,450;dagger,2379,5;spike sword,2383,1000;rapier,2384,40;sabre,2385,150;magic longsword,2390,600000;fire sword,2392,4000;giant sword,2393,17000;carlin sword,2395,1000;ice rapier,2396,1000;longsword,2397,50;silver dagger,2402,500;knife,2403,3;combat knife,2404,6;sickle,2405,10;short sword,2406,80;bright sword,2407,3000;warlord sword,2408,100000;serpent sword,2409,900;poison dagger,2411,50;katana,2412,40;broadsword,2413,350;golden sickle,2418,100;scimitar,2419,150;heavy machete,2442,90;epee,2438,100000;bone sword,2450,100;djinn blade,2451,600000;avenger,6528,200000;demonrage sword,7382,10000;relic sword,7383,25000;mystic blade,7384,10000;crimson sword,7385,500;mercenary sword,7386,20000;justice seeker,7390,70000;thaian sword,7391,15000;dragon slayer,7402,15000;assassin dagger,7404,15000;havoc blade,7405,7000;blacksteel sword,7406,2000;haunted blade,7407,10000;wyvern fang,7408,2000;bloody edge,7416,10000;runed sword,7417,10000;nightmare blade,7418,30000;crystal sword,7449,600;emerald sword,8930,300000;jagged sword,8602,80000;golden sword,8931,1000000;calamity,8932,70000;war hammer,2391,900;morning star,2394,100;mace,2398,30;staff,2401,25;crowbar,2416,50;battle hammer,2417,150;thunder hammer,2421,300000;iron hammer,2422,50;clerical mace,2423,200;silver mace,2424,100000;dragon hammer,2434,2000;skull staff,2436,6000;daramanian mace,2439,200;hammer of wrath,2444,75000;crystal mace,2445,30000;studded club,2448,35;bone club,2449,50;arcane staff,2453,30000;lich staff,3961,15000;banana staff,3966,1000;brutetamers staff,7379,2000;mammoth whopper,7381,400;diamond sceptre,7387,4000;orcish maul,7392,1000;sapphire hammer,7437,7000;shadow sceptre,7451,100000;spiked squelcher,7452,500;queens sceptre,7410,2000000;abyss hammer,7414,500000;cranial basher,7415,10000;jade hammer,7422,70000;lunar staff,7424,7000;taurus mace,7425,600;amber staff,7426,8000;chaos mace,7427,10000;dragonbone staff,7430,3000;furry club,7432,500;dark trinity mace,8927,700000;obsidian truncheon,8928,400000;stomper,8929,250000;battle axe,2378,100;hand axe,2380,20;halberd,2381,400;double axe,2387,300;hatchet,2388,25;great axe,2415,20000;obsidian lance,2425,500;naginata,2426,1000;guardian halberd,2427,5000;orcish axe,2428,200;barbarian axe,2429,300;knight axe,2430,1000;stonecutter axe,2431,600000;fire axe,2432,7000;dwarven axe,2435,1000;daramanian waraxe,2440,900;daramanian axe,2441,400;ravagers axe,2443,50000;twin axe,2447,60000;war axe,2454,10000;beastslayer axe,3962,2000;ruthless axe,6553,70000;headchopper,7380,4000;vile axe,7388,60000;heroic axe,7389,15000;relic axe,7411,40000;butchers axe,7412,70000;titan axe,7413,40000;bloodslayer axe,7453,40000;destroyers axe,7454,60000;ice double axe,7455,90000;cursed axe,7433,30000;royal axe,7434,150000;black axe,7435,300000;angelwing axe,7436,200000;"/>
    </parameters>
</npc>

local keywordHandler = KeywordHandler:new()
local npcHandler = NpcHandler:new(keywordHandler)
NpcSystem.parseParameters(npcHandler)

function onCreatureAppear(cid)            npcHandler:onCreatureAppear(cid)            end
function onCreatureDisappear(cid)        npcHandler:onCreatureDisappear(cid)            end
function onCreatureSay(cid, type, msg)        npcHandler:onCreatureSay(cid, type, msg)        end
function onThink()                npcHandler:onThink()                    end

npcHandler:addModule(FocusModule:new())

    -- Callback onBuy() function. If you wish, you can change certain Npc to use your onBuy().
    function ShopModule:callbackOnBuy(cid, itemid, subType, amount, ignoreCap, inBackpacks)
        local shopItem = nil
        for _, item in ipairs(self.npcHandler.shopItems) do
            if(item.id == itemid and item.subType == subType) then
                shopItem = item
                break
            end
        end

        if(shopItem == nil) then
            error("[ShopModule.onBuy]", "Item not found on shopItems list")
            return false
        end

        if(shopItem.buy == -1) then
            error("[ShopModule.onSell]", "Attempt to purchase an item which only sellable")
            return false
        end

    -- Callback onSell() function. If you wish, you can change certain Npc to use your onSell().
    function ShopModule:callbackOnSell(cid, itemid, subType, amount, ignoreCap, inBackpacks)
        local shopItem = nil
        for _, item in ipairs(self.npcHandler.shopItems) do
            if(item.id == itemid and item.subType == subType) then
                shopItem = item
                break
            end
        end

        if(shopItem == nil) then
            error("[ShopModule.onBuy]", "Item not found on shopItems list")
            return false
        end

        if(shopItem.sell == -1) then
            error("[ShopModule.onSell]", "Attempt to sell an item which is only buyable")
            return false
        end