Error Trying to add Calculated Items to a pivot table
 

While trying to add a calculated item to a pivot table I get the
following error

"The item cannot be added or modified. There may not be enough memory,
the maximum number of items allowed in a field may have been reached,
or if a Visual Basic macro is performing the operation, the macro may
be incorrect

Simply the Pivot Table or check the macro for errors, and then try the
operation again."

I am doing this manual so the macro issue is not the problem. It must
be the memory issue, but how do I know how much memory is being used.
The workbook has about 7 pivot tables in it and it's a smaller version
of the same file and therefore is using less memory (which is the
point of recreating the old file). How do I find out if it's the
memory issue. Also my pivots all pull off the same data.

John