A strange delay in interaction between 2 subforms

[Galina]

Hello
I have an application in MS Access 2K.
A form contains 2 subforms. Each subform is based on it's own table.
One table contains a field Total. Another one contains a field Points.
The field Total is a sum of Points in several records. Before to open
the form, Totals are pre-calculated.
Users enter points into the column Points via one subform. I want to
reflect the change in points summary in another subform. To do so, I
have a total field [Points total] (invisible) in the header of the
points subform, which has a control source =Sum([Points]). In an
AfterUpdate event of the Points subform I have a command:
Me.Parent!frmScreening.Form!Total = Me![Points total]
It works, but with a strange delay: when I update points in one
record, the total in the header of the subform is updated, but the
total in the another subform is not. When I update points in another
record, the total in the other subform is updated to show the first
change only. When I update points in the third record, the total in
the other subform is updated to show the first and second changes, and
so on. The last change of points is not shown at all until the form
is closed and opened again.
What would be the best way to show total points in the second subform
immediately after the change happened in the first subform? Any help
will be really appreciated. Thank you.
Galina