Mccoy,
It is not clear what you are doing here. I agree with Karl that a
SetValue macro is not appropriate here. I do not necessarily agree that
an Update Query is right either. That would assume that the control on
the main from is bound to a field in the table behind the main form. Is
it? If so, then what you are doing is almost certainly incorrect
database practice. It is very rare for it to be justified storing data
redundantly. If, on the other hand, the main form control is unbound,
and is for display purposes to show aggregated subform data or some
such, then this should simply be handled directly in the Control Source
of the control on the main form, and no macro or action query applies.
So, if you need more detailed help with this, can you please post back
with further explanation, with example.