_RefMappingShopWithTab more than two shop in same NPC

Hello, today I experienced very strange problem. I have created npc and added two shops for it. For example STORE_CUSTOM_GROUP1 and STORE_CUSTOM_GROUP2, each group have 3 tabs. Tabs is:

STORE_CUSTOM_TAB1
STORE_CUSTOM_TAB2
<....>
STORE_CUSTOM_TAB6

So, till there are only two groups on the same NPC everything is okay, but when I add third group (STORE_CUSTOM_GROUP3) everything starts to fuck up.
STORE_CUSTOM_GROUP3 have only one tab, but when I buy something from it, I get different item, it changes after teleport/restart. Strange thing is that visualy everything is okay, but the server thinks than I buy items from STORE_CUSTOM_GROUP1 third tab (STORE_CUSTOM_TAB3) and this only happens when I add third group to the same NPC.

Bump :)