Warning for Dynamic Combobox list - ms-access

Question

I have a combobox that builds it's list upon first usage. I know that the way I want "NotInList" to behave isn't conventional - I don't want to waste adding the item to a table separate from the needed entry, but I'd like to still warn about an item that hasn't been used yet, so that the user has to think twice before accepting the entry.
Once the user adds the item, it will automatically appear in the list next time because the data source for the combo box is as follows:
SELECT tbl_SP.PROGRAM
FROM tbl_SP
GROUP BY tbl_SP.PROGRAM
HAVING (((tbl_SP.PROGRAM) Is Not Null And (tbl_SP.PROGRAM)<>""));
I tried this:
Private Sub cmbPROGRAM_NotInList(NewData As String, Response As Integer)
If MsgBox("'" & Chr(34) & NewData & Chr(34) & " hasn't been used yet. Add to list? ", vbQuestion + vbYesNo, "Add - " & NewData & "?") = vbYes Then
Response = acDataErrAdded
End If
End Sub
but of course, Access wants the item to actually exist before it will release the error. And...if I set LimitToList to "No" then the user doesn't get a warning.
How can I achieve this behavior?
Ok, I tried this which works fine if the user selects YES, but becomes more complicated when the user selects "NO"
Public Function ReturnsRecords(strSQL As String) As Boolean
Dim d As DAO.Database
Dim arr(1 To 3) As DAO.Recordset
'Dim rs As DAO.Recordset
'assume 3 items in array above
Set d = CurrentDb
Set arr(1) = d.OpenRecordset(strSQL)
' MsgBox "Record Count is " & arr(1).RecordCount
If arr(1).RecordCount > 0 Then
ReturnsRecords = True
Else
ReturnsRecords = False
End If
Set d = Nothing
End Function
Private Sub cmbPROGRAM_BeforeUpdate(Cancel As Integer)
Dim strSQL As String
strSQL = "Select * from LU_PROGRAM where PROGRAM ='" & Me.cmbPROGRAM & "'"
If ReturnsRecords(strSQL) = False Then
If MsgBox("'" & Chr(34) & Me.cmbPROGRAM & Chr(34) & " hasn't been used yet. Add to list? ", vbQuestion + vbYesNo, "Add - " & Me.cmbPROGRAM & "?") = vbNo Then
Cancel = True
' how do I reset this? Me.cmbPROGRAM.Text = Null
End If
End If
End Sub
How do I clear the combobox if the user selects NO? If I select me.undo, that will undo all of the entries, but I just want to clear the combobox.
Incidentally, the form is totally unbound and doesn't accept an entry until the user selects "Save"

Answer 1

First, I'm not quite sure what you wish to achieve ...
Then, educate the users to press Escape to cancel. This is mandatory wisdom when operating an Access application.
For your code to work, you can't change the content of a control in the BeforeUpdate event. So try the AfterUpdate event with either:
Me!cmbPROGRAM.Text = ""
or:
Me!cmbPROGRAM.Value = Null