PPS in sharepoint 2010 error for analytic grid "The length of the string exceeds the value set on the maxJsonLength property. "

Question

I am using performance point and using the member filter connected to analytic grid.In the connection formula I have written something like below

Drilldownleveltop(
Drilldownleveltop(
Drilldownleveltop(
Drilldownleveltop(
DrilldownLevelTop(TopCount(<<SourceValue>>, 5, [Measures].[Net Cost Global]),
3,,[Measures].[Net Cost Global]),
3,,[Measures].[Net Cost Global]),
3,,[Measures].[Net Cost Global]),
3,,[Measures].[Net Cost Global]),
3,,[Measures].[Net Cost Global])

But I am getting the error message "Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property."

The same query works fine in sql server 2008 and i am getting top10 at each level. Please let me know what changes should i make it to work.

Thanks