TOPCount mdx query at different dimension hierarchy levels



I have a dimension called location having a hierarchy Country, State, City.......

I written an mdx query which will return top 3 customers having high sales amount.

Find the mdx query below: Created the below mdx as named set in cube.

TOPCOUNT([Customer].[Customer Name].[Customer Name],3,[Measures].[Sales Amount])

SELECT

NON EMPTY TOPCOUNT([Customer].[Customer Name].[Customer Name],3,[Measures].[Sales Amount])

ON COLUMNS,

NON EMPTY { [Measures].[Sales Amount] } ON ROWS

FROM [Cube]

I created a chart in PPS (performance point server) for Top 3 customers by Sales Amount,

having Sales Amount on series, Named set on bottom axis.

It works fine when i slice it through country level but if i drill down to state and city

level it is not working fine.

The same top 3 customers whose has high sales at country level is divided and given at

state and city level when i do a drill down. But if i do a query in database the list of top

3 customers at state level is slight different from the result i get from drill down from

country to state.

Please help me on this..... Thanks in Advance.