Brian,

Because the # D2:D200 # is not qualified as being in sheet 1 XL will assume
that it is in the active sheet. Try:

=SUMPRODUCT(--(Sheet1!B2:B200="D"),--(Sheet1!C2:C200=4),Sheet1!D2:D200)

--
HTH

Sandy
In Perth, the ancient capital of Scotland


with @tiscali.co.uk


"Brian" wrote in message
...
=SUMPRODUCT(--(Sheet1!B2:B200="D"),--(Sheet1!C2:C200=4),D2:D200)

When I use this formula, the result is 0.

A B C D

1 D 4 2
2 B 2 3
3 D 5 5
4 A 2 2