Running total for Pivot with two row labels

[bukimi]

Hello,

I have a problem with adding a running total for a pivot table that has two parallel row labels.
When it's just Product_number|Sales_Value it works fine.
When I add another Row label (Product name), making it ProductNumber|ProductName|SalesValue, then Running total just gives Sales value (not a running total), no matter if I choose to sum it by name or number.

Tried using PowerPivot by adding a new measure:

=CALCULATE (
    SUM ( Sales[Sales] ),
    FILTER (
        ALL (Sales[ProductNumber] ),
        Sales[Number] <= MAX (Sales[Number])
    )
)

but it also works only when pivot table has only one row label.