I have two simple tables in Excel 2010 - Products and Sales:

Then I linked them to PowerPivot - and here a relationship was created from Sales.ProductId to Products.Id - like this:

Now I'm trying to create a Pivot, which for each product in the Sales table also shows me the category and PurchasePrice from ProductTable. However, here I am stuck - because the relationship is somehow wrong. When setting up Pivot, I get a message Relationship may be neededeven if the relationship already exists. The resulting table with the wrong calculation looks like this:
although I'm actually trying to do this:

, Sales PowerPivot RELATED DAX, , , , ...
.