To use the report builder you must install .NET framework 3.5
I recently had a customer who tried to create new Reporting Services report with Report Builder from her sharepoint team site. And she got this error : “To use the report builder you must install .NET framework 3.5″.
The problem was that the .NET framework 3.5 was already installed on her computer.
Well, this is because IE9 doesn’t detect the installed .NET framework 3.5.
To be able to start the Report Builder she needed to run the web site in Compatibility view.
Happy reporting !