npc sell/buy problem

[Makin]

Hello, the problem is that I cannot buy or sell the item. And there is no error in the console.
tfs 1.5

xml.

<?xml version="1.0" encoding="UTF-8"?>

<npc name="Talon Trader" script="talon.lua" walkinterval="2000" floorchange="0">
    <health now="100" max="100" />
    <look type="302" head="20" body="39" legs="45" feet="7" addons="0" />

    <parameters>
    <parameter key="module_shop" value="1" />
    <parameter key="message_greet" value="Hello, |PLAYERNAME|! I buy all talons 10 zeni each." />
    <parameter key="shop_sellable" value="talon,2151,100;" />
    </parameters>

</npc>

lau.

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())