data source reference is not valid - Excel error when adding a pivot table
I've had this error a few times but never figured out
With the help of a few posts around the web I finally found out the reason.
If you have opened a none excel file like a csv file, then you get this error
"Data source reference is not valid" really helpful.
The solution is to save your spreadsheet as an xls or xlsx file and heh
presto you can create the pivot table.