Here is the formula that I am using:

=SUMPRODUCT(('GA Data'!$CK$27:$CK$44>=$A$4)*('GA Data'!$CK$27:$CK$44<=$A$7),'GA Data'!CM2:CM19)

where: CK is Date, A4 is Start Date, A7 is End Date, CM is data to be summed.

Currently this formula is returning a 0 (when it should be ~700). When I remove the upper limitation portion of the formula *('GA Data'!$CK$27:$CK$44<=$A$7) then the correct value is returned.

The problem is that I need to include the Upper Limits so I can create a monthly report. Any ideas?