I don't know about PowerPivot but, in T-SQL, you would need to create an OUTER JOIN relationship with your date table and return the month date from the date table instead of from the data table. You need to do the same with PowerPivot. I'd tell you how but, like I said, I don't even know how to spell "PowerPivot". 😀
--Jeff Moden
Change is inevitable... Change for the better is not.