Lua 050-function.lua error

[OnixServer]

this is my server error message:

[22:5:08.270] The Forgotten Server, version 0.3.7_SVN (Crying Damson)
[22:5:08.270] Compiled with GNU C++ version 3.4.5 (mingw special) (x86_64: 0) at
Apr 3 2013, 16:46:30.
[22:5:08.270] A server developed by Elf, Talaturen, Dalkon, BeniS, Tryller and K
ornholijo.
[22:5:08.270] Visit our forum for updates, support and resources: http://otland.
net.

[22:5:08.270] >> Loading config (config.lua)
[22:5:08.270] > Opening logs
[22:5:08.270] > Using SHA1 encryption
[22:5:08.270] >> Checking software version...
[22:5:08.270] > Ignoring version check, using SVN
[22:5:08.400] >> Loading RSA key
[22:5:08.400] > Calculating dmp1, dmq1 and iqmp for RSA... done
[22:5:08.400] >> Starting SQL connection
[22:5:08.400] >> Running Database Manager
[22:5:08.772] > Optimized database.
[22:5:08.772] >> Loading items (OTB)
[22:5:08.792] >> Loading items (XML)
[22:5:09.072] >> Loading groups
[22:5:09.072] >> Loading vocations
[22:5:09.072] >> Loading outfits
[22:5:09.072] >> Loading chat channels
[22:5:09.082] >> Loading script systems

[!] -> Checking demon oak lib...
[!] -> 0 problems loaded in 0.005 seconds.

[!] -> Demon Oak Lib loaded in 0.005 seconds.

[22:5:09.227] > Loading weapons... done.
[22:5:09.227] > Preparing weapons... done.
[22:5:10.937] > Loading spells... done.
[22:5:20.988] > Loading actions... done.
[22:5:21.786] > Loading talkactions... done.
[22:5:28.271] > Loading movements... done.
[22:5:28.671] > Loading creaturescripts... done.
[22:5:28.801] > Loading globalscripts... done.
[22:5:28.801] >> Loading mods...
[22:5:28.801] > Loading firstitems.xml... done, but disabled.
[22:5:28.831] > Loading ZaoShard.xml... done.
[22:5:28.831] > 2 mods were loaded (1 disabled).
[22:5:28.831] >> Loading experience stages
[22:5:28.831] >> Loading skills stages
[22:5:28.841] >> Loading quests
[22:5:28.841] >> Loading monsters
[22:5:29.276] >> Loading raids
[22:5:29.286] >> Loading map and spawns...
[22:5:31.855] > Map size: 33536x33024.
[22:5:31.855] > Map descriptions:
[22:5:31.855] "Saved with Remere's Map Editor 2.2"
[22:5:31.855] ""
[22:5:52.768] > Loading time: 23.482 seconds.
[22:5:54.098] > Parsing time: 1.33 seconds.
[22:7:19.566] > Synchronization time: 85.468 seconds.
[22:7:19.616] > Unserialization time: 0.05 seconds.
[22:7:19.616] >> Checking world type... Optional PvP
[22:7:19.616] >> Starting to dominate the world... done.
[22:7:19.616] >> Initializing game state and binding services...
[22:7:20.766] > Global IP address(es): x
[22:7:20.766] > Local IP address(es): x
[22:7:20.776] > Bound ports: 7171 7172
[22:7:20.776] >> Everything smells good, server is starting up...
[22:7:21.781] >> Server Online!

[22:8:17.543] Maintenance has logged in.

[22:8:35.319] [Error - NpcScript Interface]
[22:8:35.319] (Unknown script file)
[22:8:35.319] Description:
[22:8:35.319] data/npc/scripts/esrik.lua:144: attempt to call global 'customCall
backOnBuy' (a nil value)
[22:8:35.319] stack traceback:
[22:8:35.319] data/npc/scripts/esrik.lua:144: in function <data/npc/scripts/es
rik.lua:143>

[22:10:00.369] [Error - NpcScript Interface]
[22:10:00.369] data/npc/scripts/Pompan.luanCreatureSay
[22:10:00.369] Description:
[22:10:00.369] data/npc/lib/npcsystem/npchandler.lua:647: attempt to compare boo
lean with number
[22:10:00.379] stack traceback:
[22:10:00.379] data/npc/lib/npcsystem/npchandler.lua:647: in function 'say'
[22:10:00.389] data/npc/scripts/Pompan.lua:14: in function 'callback'
[22:10:00.389] data/npc/lib/npcsystem/npchandler.lua:455: in function 'onCreatu
reSay'
[22:10:00.389] data/npc/scripts/Pompan.lua:8: in function <data/npc/scripts/Pom
pan.lua:8>

the error appears when using the trade after storage of some npc
how can I solve this problem? plz help me!