Hi All,

I'm using the following formula to return data in a sheet:

=SUMPRODUCT(--(Demand1!$A$1:$A$9731=$A21),(--Demand1!$B$1:$B$9731=G$19),(--Demand1!$D$1:$D$9731=$B$17),(Demand1!$C$1:$C$9731) )

In the sheet with the formula, I have part numbers down column A, dates
across rows (19 in this case), and another text qualifier in B17.

In sheet "Demand1" I have 4 columns - A has part numbers, B has dates, C has
quantity (the value I want returned), and D has the text qualifier.

My problem is that the formula sometimes works and sometimes doesn't - it is
very tempermental. I've tried matching all the formating, and still
sometimes it does not work.

Anyone have any ideas?

Thanks,