Pivot Table: “Cannot Group That Selection” error

[steveski]

I have a data entry sheet with a column titled “Start Date”. This colum
contains only dates.

I have a Pivot Table based on the data entry sheet. In the Pivot Tabl
“Start Date” is a Column Field. Start Date is also used as the dat
field (Count of Start Date).

I clicked on the “Start Date” In the Column Filed area and selecte
Grouping by Month & Year.

While I was developing the spreadsheet, I used some arbitrary dates i
the Start Date column, and the grouping worked fine. Then I brought i
a column of dates from the ‘real’ data entry sheet, and now th
grouping is not functional (“Cannot Group That Selection” error).

Can you tell me some possible causes of this error?

Thanks

 

[Ken Wright]

A blank or non-date entry somewhere in that field in the source data. Maybe a
date that is actually text, albeit it looks like a date.