enforcing business logic

hi,

we are working in oracle applications 11i.

 In Oracle Inventory - Miscelleaneous transaction -INVTTMTX form I have a business logic that I need to enforce on issuing, that depends on the value entered in the descriptive flexfiled segment values (transaction history DFF).

I have contacted Oracle Support after clearing out that it's a customization thing and I can't get their help they suggested I add custom code to CUSTOM.pll.

My info; pls correct me if I'm wrong, is to use the diagonistics-> Custom Code-> Show custom events to get the right event. Well  !!!! there was no WHEN_VALIDATE_RECORD EVENT after inserting the data in the DFF. the only event was