subform inappropriately creating blank record

I have a form with a subform. They are connected by SchoolID. The subform
has an autonumber field GroupID. The from(s) come up blank with the GroupID
field indicationg "autoNumber". When I start to enter information into the
subform the GroupID creates a number for the record. Looks great until I
open the table. The form is creating a blank record before the actual
record. Why is this happening. The code behind this form is very simple.
Only 5 buttons. New group, next group and previous group and open time table
(all on sub form) and Close form on the main form

Thanks for any insights anyone can provide.