Combo Edits "not triggering" with Fluid Expense Reports

PeopleSoft 9.2.51

PeopleTools 8.61.07

I need suggestions as to where to check to verify that Combo Edits have been configured correctly for Fluid Expense reports. Although combo edit has been selected in the Expense Installation Options, I'm apparently missing something. I enter an Expense Report with an invalid chartfield string, and I receive no feedback from the system telling me the combination is invalid. I've reviewed areas covered by PeopleBooks, and the Combo Edit process is working in every module we currently use, such as Purchasing, Payables, and eProcurement.

Thanks,

Rick