Get distinct customers based on Time, Product Hierachey

Hi All, 

I am using SQL Server 2005 and AdventureWorks. I have created a cube with Fact : FactInternetSales, DimCategory (other 2 related tables) and Time dimension is also there. I have created a measure called "Unique Customers" using distinct(customer_key) from FactInternetSales.

When I am trying to browse the cube, I used Product Catalog Hierarchy (Product, Category, SubCategory) in  Rows and Calendar Hierarchy in Column and Major is "Unique Customer" (distinct customer_key in FactInternetSales). The result is not satisfactory.

My goal is the find out Unique Customers based on the product they bough in different month, year and Quarter. Please see the Screenshot. Am i messing up something ? Please advise.

Thanks,

Sam BI