Set Analysis PY Value

[#1]

Hello,

I have this expression in a pivot table to get the previous year sales:

=sum(aggr(sum({<MonthYear,YearMonth={"$(=YearMonth-100)"}>}SalesValue)/100, Product,Region))

it works fine until I select, for example, 2 YearMonth!?

I think it's because there are values that exists in one YearMonth, but not in the other, so their is nulls in the value columns...

Any suggestions?

Regards,

Francisco