Problems with EpiCombo when retrieving data when EpiBinding is set to a UD field

I have an EpiCombo box that is linked to our UD02 tables, with a filter on Key1 to select the proper set of data, then uses the Key2 field for a code to save to the UD field. If I have RetrieveOnActivate true, it pulls the data in correctly, but if I have a value set in the UD field, it does not display what has previously been selected from the list. If I then set RetrieveOnActivate to false, it then displays the value from teh EpiBinding, but does not populate the list. I know I am probably missing something, maybe I have to set the binding value in code, but does anyone have any ideas for this issue?