An empty cell is read off as 0, a result that gets mapped to a January date.

Assuming that you have true dates in A1:A10 and you're interested to
count, say, Jan 2005 dates.

In C1 enter the first of the month/year of interest as a true date: 1-Jan-05

In C2 enter:

=SUMPRODUCT(--(DATE(YEAR(A1:A10),MONTH(A1:A10),1)=C1))

The result should be 3.

JRod wrote:
Hi, guys,
I have a Range A1:A10 with the following:
A1 - 01-Jan
A2 - 02 -Jan
A3 - 01-Feb
A4 - 02-Feb
A5 (Blank)
A6(Blank)
A7(Blank)
A8 - 03-Jan
A9(Blank)
A10(Blank)

If I want to count how many cells have "Jan" with the formula:
=SUMPRODUCT(--(TEXT($A$1:$A$5;"mmm")="Jan"))

it gives me the number 8. However, really the number is 3.
But, if the above formula is with "Feb", the number is correct, i.e. - 2.

I understood that for unknown reason to me, the first formula counts the
blank cells as they are with "Jan" too. So, if I write:
=SUMPRODUCT(--(TEXT($A$1:$A$10;"mmm")="Jan"))-SUMPRODUCT(--ISBLANK(A1:A10))
the result is now correct, I mean, number 3.

Any ideas for this? Thanks in advance.