"Laura Wild" wrote:

..
=SUM(IF(('cat12-Dec04-Oct-05'!A8:A30553="12/1/2004")+('cat12-Dec04-Oct-05'!U
8:U30553="Sustain"),('cat12-Dec04-Oct05'!P2:P30547)))

Try instead:

=SUMPRODUCT(
('cat12-Dec04-Oct-05'!$A$8:$A$30553= --"12/1/2004")
*('cat12-Dec04-Oct-05'!$U$8:$U$30553="Sustain"),
'cat12-Dec04-Oct-05'!$P$8:$P$30553)

Note that the 3 ranges need to be identical (your col P range was
inconsistent), and a "--" is placed in front of the text date,
viz.: --"12/1/2004", to coerce it into a real date for matching with the
real dates in col A
--
Rgds
Max
xl 97
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