Gos-C,

Try breaking it down by parts:

=SUMPRODUCT([Book1.xls]Sheet2!C4:C1550="AB",1)

=SUMPRODUCT([Book1.xls]Sheet2!M4:M1550<"",1)

=SUMPRODUCT(DATE(YEAR([Book1.xls]Sheet2!M4:M1550),MONTH([Book1.xls]Sheet2!M4:M1550),1)<DATE(YEAR([Book1.xls]Sheet2!X4:X1550),MONTH([Book1.xls]Sheet2!X4:X1550),1))

=SUMPRODUCT([Book1.xls]Sheet2!R4:R1550),1)

Which part(s) throw an error?

HTH,
Bernie
MS Excel MVP


"Gos-C" wrote in message
...

I tried all the suggestions (and check the dates, which appear to be OK)
but I am still getting the same error.

Gos-C


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Gos-C


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