You have transition formula evaluation turned on in this particular sheet,
click the office buttonexcel options
select advanced and scroll to the bottom and under "lotus compatibility
settings for" select this sheet and clear that check mark


In previous excel versions it is under toolsoptionstransition

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Regards,


Peo Sjoblom

"Brad" wrote in message
...
Excel 2007

On one sheet
=date(2008,13,1) provides the correct answer of 1/1/2009

copy that equation to a different sheet (in the same workbook) provides
the
incorrect answer of #NUM!

copy that equation to a third sheet (in the same workbook) provides the
correct answer of 1/1/2009

Can't figure why I'm getting the #NUM!. Any suggestions?