I am using the following code for adding to a Combo Box when an item is
entered that's not in the list:

Private Sub Customer_NotInList(NewData As String, Response As Integer)
   On Error GoTo Customer_NotInList_Err
   Dim intAnswer As Integer
   Dim strSQL As String
   intAnswer = MsgBox("Customer " & Chr(34) & NewData & _
       Chr(34) & " does not exist." & vbCrLf & _
       "Would you like to add it?" _
       , vbQuestion + vbYesNo, "Customers")
   If intAnswer = vbYes Then
       strSQL = "INSERT INTO Customers_Table(CU_Customer) " & _
                "VALUES ('" & NewData & "');"
       DoCmd.SetWarnings False
       DoCmd.RunSQL strSQL
       DoCmd.SetWarnings True
       MsgBox "The new customer has been added." _
           , vbInformation, "Customers"
       Response = acDataErrAdded
   Else
       MsgBox "Please choose an existing customer then." _
           , vbInformation, "Customers"
       Response = acDataErrContinue
   End If
Customer_NotInList_Exit:
   Exit Sub
Customer_NotInList_Err:
   MsgBox Err.Description, vbCritical, "Error"
   Resume Customer_NotInList_Exit
End Sub

It's not working and I'm not sure why...  When I type a new value into my
form I get the "Customer ___ does not exist. Would you like to add it?"
message.  If I select No, I get the proper message.  If I select yes, it
doesn't add it to the table.  Instead I get the follow error message:

Cannot find output table 'Customers_Table'.

But that is the name of my table!