My ss contains links to another spreadsheet. In col A are dates. I need to
add only those pieces of information that are valid dates and not include
the links, but I'm having a bit of difficulty. Here is the formula I used,
but I get #value error.

=SUMPRODUCT(--(MONTH(Burlington!$A$2:$A$201)=10),--(YEAR(Burlington!$A$2:$A$
201)=2004),--ISNUMBER(--(MONTH(Burlington!$A$2:$A$201))))

Maybe is not possible?

Thanks!