Hi all,

I'm stumped and have spent many hours puzzling over this.  I have two related comboxboxes, cboClient and cboCoverage on an EventBO maintenance form.   Each is bound to an FK on the EventBO record (CLI_ID and COV_ID). 

When the user selects a new Client, I want the cboCoverage to requery showing only the coverages for this particular client and I want to set its selected value in code to a particular one of the coverage choices.  The logic for this doesn't matter here (I am actually setting the recommended coverage for that client based on several other variables...); here is an ultra simplified version setting a fixed value in code just for demo:

 Private Sub cboClient_SelectionChangeCommitted(sender As Object, e As System.EventArgs)_
     Handles cboClient.SelectionChangeCommitted
        Me.cboCoverage.Requery()
        Me.cboCoverage.SelectedValue = 50022155  ' simplified for demo
 End Sub

This works fine when editing an existing record.  It fails on a new record with the following error:

System.InvalidCastException was unhandled by user code
  Message=Conversion from type 'DBNull' to type 'Integer' is not valid.
  Source=Microsoft.VisualBasic
  StackTrace:
       at Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(Object Value)
       at ThomBillerBOLibrary.EventBO.FieldDescriptor.SetValue(Object component, Object value) in E:\ThomBiller\ThomBillerBOLibrary\ThomBillerBOLibrary\EventBO.Designer.vb:line 3003
       at System.Windows.Forms.BindToObject.SetValue(Object value)
       at System.Windows.Forms.Binding.PullData(Boolean reformat, Boolean force)
  InnerException:

Specifically, this is happening as the EventBO is trying to set the CLI_ID value based on the cboClient selection:

        Public Overrides Sub SetValue(ByVal component As Object, ByVal value As Object)
            Select Case Me.Field
                Case EventBOFieldNames.EVE_ID
                    DirectCast(component, EventBO).EVE_ID = CType(value, System.Int32)
                Case EventBOFieldNames.OLDPK
                    DirectCast(component, EventBO).OLDPK = CType(value, System.String)
                Case EventBOFieldNames.CLI_ID
                    DirectCast(component, EventBO).CLI_ID = CType(value, System.Int32)

What is so odd is that on a new EventBO record, I can either requery() the related cbo or set its selectedvalue without error, but not both.  If I am simply editing an existing EventBO record, I can do both.

TIA,

Larry