Check and make sure calculation is set to automatic.

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Biff

"Mango" wrote in message
...
I'm using Excel 2003, and have been making reports that use a lot of SUM
and
SUM IF formulas. For some reason the formulas have stopped working, even
though when I click on the destination cell, the formula is correctly
expressed in the address bar. If I re-enter the formula, it does what it's
supposed to, but only that one time. If I come back and add or delete data
in
the series, nothing changes in the destination cell. Some of these
formulas
are simply adding numbers in a column, but some express results in graphs
that pull data from different worksheets.