issue in roll up aggregate totals in charts

[dsg1]

I have a report with multidimentional data source which have a bar chart which shows Products in Y-axis and have actual and target revenue measures in series.

My requirement is apart from the individual actual/target revenues, I have to show another bar below the standard bars (actual / target) in the chart which shows the total actual revenues for all the products i.e summation of all the actual revenues of that particular level which is being displayed.   
   
I have dragged the actual revenue measure besides product in the categories area.

The issue is : for the highest level it is showing correct data but when drilling down to sub levels..the chart is continuing to show the total actual revenue of the top level in the hierarchy.

I have tried changing the aggregate / roll up properties, also 'for' clause but of no use.

Is there a way I can achieve this?

Thanks
dsg