Lua NPC ERROR: OnBuy | TFS 0.4 | HELP!!!

[drhoficial]

I've tried looking for solutions here on the forum and so far I haven't found anything that can help me.
ERROR:
[0:30:19] [Error - NpcScript Interface]
[0:30:19] (Unknown script file)
[0:30:19] Description:
[0:30:19] data/npc/lib/npcsystem/npchandler.lua:263: bad argument #1 to 'unpack' (table expected, got nil)
[0:30:19] stack traceback:
[0:30:19] [C]: in function 'unpack'
[0:30:19] data/npc/lib/npcsystem/npchandler.lua:263: in function 'processModuleCallback'
[0:30:19] data/npc/lib/npcsystem/npchandler.lua:440: in function 'onBuy'
[0:30:19] data/npc/lib/npcsystem/modules.lua:1302: in function <data/npc/lib/npcsystem/modules.lua:1301>
NPC:
<?xml version="1.0" encoding="UTF-8"?>
<npc name="Carlinhos" script="default.lua" floorchange="0">
<health now="150" max="150"/>
<look type="134" head="114" body="113" legs="113" feet="113" corpse="2212"/>
<parameters>
<parameter key="module_shop" value="1" />
<parameter key="message_greet" value="Hallow |PLAYERNAME|.I sell yellow potions, mana potions and polly potions, mas lembre-se eh mais barato vc fabrica-las do que compra-las, say {trade}" />
<parameter key="shop_buyable" value="yp,2269,120; mp,2272,180; pp,2270,220" />
</parameters>
</npc>