List Customization problem

We have two list customizations associated with the defects module, both were created using the Script Generator-list customization feature within the workflow module. The first customization works like a champ. The second works only when the user adds a defect. If the user comes back and edits the field the list is not populating as programmed.  I have included the code below. For BG_USER_04 field name is Application. We are using QC 11 patch 13. I have tried this in a test project before I deployed to the production project, just to ensure that it worked, which it did. I then deployed to the production, under the assumption the list script would work.

The intention of the workflow was the user selects Application Group, then select the Application. In our configuration I have the Application list populated with a default value of "Select Application Group first", just to alert the user the correct action. After the defect is generated, the user is unable to select a value other than "select application group first" regardless of which Application Group selection is made. Each application group has at least 3 items.

Any help to resolve this would be greatly appreciated. 

Sub WizardListCust
' This subroutine had been automatically generated by "Script Generator - List Customization".
' Any modification you make will be overwritten next time you use the generator.

    ' BEGIN: When primary Type value is changed, Resolution's selection list will change.
    Select Case Bug_Fields("BG_USER_01").Value
        Case "Sys Improvement Request (SIR)"
            Bug_Fields("BG_USER_02").List = Lists("Resolution-SIR")
        Case "Sys Trouble Report (STR)"
            Bug_Fields("BG_USER_02").List = Lists("Resolution")
        Case Else
            Bug_Fields("BG_USER_02").List = Lists("Resolution-STR")
    End Select
    ' END: When primary Type value is changed, Resolution's selection list will change.

    ' BEGIN: When primary Application Group value is changed, Application's selection list will change.
    Select Case Bug_Fields("BG_USER_05").Value
        Case "COP"
            Bug_Fields("BG_USER_04").List = Lists("App-COP")
        Case "Documentation"
            Bug_Fields("BG_USER_04").List = Lists("App-Documentation")
        Case "Hardware"
            Bug_Fields("BG_USER_04").List = Lists("App-Hardware")
        Case "NAV"
            Bug_Fields("BG_USER_04").List = Lists("App-NAV")
        Case "Other"
            Bug_Fields("BG_USER_04").List = Lists("App-Other")
        Case "RADAR"
            Bug_Fields("BG_USER_04").List = Lists("App-RADAR")
        Case Else
            Bug_Fields("BG_USER_04").List = Lists("Application")
    End Select
    ' END: When primary Application Group value is changed, Application's selection list will change.

End Sub