If you’re seeing the “Cannot group that selection” error message when trying to group pivot tables, it is most likely because your data is invalid in some way.
One of our customers sent us some example data that was causing this problem:
If you look carefully you’ll see that one of the dates is the 29th of February, which isn’t a valid date! This was most likely a data entry error.
Pivot tables won’t allow you to group dates if there are any invalid dates within the data source. Blank cells are also considered to be invalid dates, so you must make sure that there are no blanks. If you fix your data so that there are no invalid values, the error should disappear and you should be able to group your pivot table.
Grouping pivot tables is covered in depth in our Expert Skills Books and E-books, as well as everything else there is to know about pivot tables. If you need to improve your knowledge of pivot tables and other advanced Excel features it could be of great value to you.