Counting the Number of Dates with Matching Month Criteria

[zom]

OK, here is a formula I have used until recently to total the items in a column that have a month value of 1 (January), and a year value of 2007.

=SUMPRODUCT(--(MONTH(J3:J438)=1),--(YEAR(J3:J438)=2007))

I originally calculated this quite happily in Office XP. A couple of months ago I accepted an S Office upgrade to cope with Office Vista, and on completion the spreadsheet fell apart. I get a #VALUE error. Can anyone see where I am out on this?

[daddylonglegs]

That formula looks fine to me, probably a problem with the data. The formula will fail, for instance, if you have text values in the date range, even a cell with a single space, or a "formula blank", i.e. a formula that returns ""