TOPCOUNT at different levels of hierarchy

Hi All,

I am very new to SSAS and I have a requirement where I have to filter the cube data to show top 10 items at each level of hierachy.

For example the hierarchy looks something like below...

Country-->State-->City-->so on ...

and I have to get top 10 sales amount for countries,state, city ...

the output should be somethong like... Top 10 countries net sales amount, if i click on a country it should show top 10 states net sales amount and if i click on a state it should show top 10 cities net sales amount and so on..

I tried something like below but not getting the correct output. Please someone help me with this.

SELECT
{[Measures].[Net Cost Global]} ON COLUMNS,
    { TOPCOUNT( DESCENDANTS([Dim Global Drilldown Cube].[Hierarchy].CURRENTMEMBER, 7), 10, 
      [Measures].[Net Cost Global])}
        ON ROWS

FROM
     [XXXCube]

Thanks,