You either have blanks or text fields in your dates - Find and fix.

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Regards
Ken....................... Microsoft MVP - Excel
Sys Spec - Win XP Pro / XL 97/00/02/03

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It's easier to beg forgiveness than ask permission :-)
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"Mary" wrote in message
...
I have a pivot table that I grouped the dates by month. I've been using it
for quite a while. I just refreshed it and the dates came ungrouped.And
when
I select the date field and group, I get an error message saying "cannot
group that selection.