Roger Govier replied on 03-Aug-08 10:46 AM
File received and returned.

there were a few entries in the date column that were Text entries, either
because they had been entered as text, or because there was some extra text
typed after the date itself.
Once the column of data was "cleaned", Sumproduct worked fine.

I added some named ranges of the form
=Data!$D$4:INDEX(Data!$B:$B,COUNTA(Data!$B:$B)+2)

and then the formula
=SUMPRODUCT((Vendor=$B4)*(MONTH(Invdate)=MONTH(H$3))*(Value))

Where H3:S3 contained dates for each of the 12 months that Madelyn required
the Summary for.

I would have suggested using a Pivot Table instead, but lots of blanks
within Invdate would have prevented grouping by Month.

--
Regards
Roger Govier