npc error

[godoyxd]

[18/04/2010 02:21:14] [Error - Npc interface] 
[18/04/2010 02:21:14] (Unknown script file)
[18/04/2010 02:21:14] Description: 
[18/04/2010 02:21:14] data/npc/lib/npcsystem/modules.lua:1151: bad argument #2 to 'error' (number expected, got string)
[18/04/2010 02:21:14] stack traceback:
[18/04/2010 02:21:14] 	[C]: in function 'error'
[18/04/2010 02:21:14] 	data/npc/lib/npcsystem/modules.lua:1151: in function 'callbackOnBuy'
[18/04/2010 02:21:14] 	data/npc/lib/npcsystem/npchandler.lua:263: in function 'processModuleCallback'
[18/04/2010 02:21:14] 	data/npc/lib/npcsystem/npchandler.lua:440: in function 'onBuy'
[18/04/2010 02:21:14] 	data/npc/lib/npcsystem/modules.lua:1292: in function <data/npc/lib/npcsystem/modules.lua:1291>

why im getting that error when i try to buy something?

 

[TriamerA]

number expected, got string

 

[godoyxd]

how i fix?

 

[Cykotitan]

Post the file which contains buyable items.