iif(([Measures].[Sales Value], [Item].CurrentMember.parent.parent) <> 0, ([Store Brand].CurrentMember,[Measures].[Sales Value], [Item].CurrentMember) / ([Store Brand].CurrentMember,[Measures].[Sales Value], [Item].CurrentMember.Parent.Parent)*100 , NULL)


This is how it looks now. But I DO WANT to specify the members of the set. I am able to specify one member (([Store Brand].[Shoprite]) but not two. It's probably not necessary to specify - one could just select the members. But now I wonder how one would do it.

I selected the two members and looked at the MDX that Proclarity generated - It uses the AGGREGATE function to combine the two members. I got errors when I tried to use AGGREGATE.