Glad you fixed it. If you need to do it in code some day, it would be:
Me.OrderBy = "MF_ID"
Me.OrderByOn = True
The OrderBy property value is a string containing a partial SQL statement (the part in the ORDER BY clause). You wanted the name of the field, but Me![mf_id] assigned the field's value instead. That's why it didn't work. Rick Sprague