MSCRM 2011 SSRS report throws random data with date filters

MSCRM 2011 SSRS report throws random data with date filters:

Hi All, we have SSRS report in MSCRm 2011 (SQL report) which has begin date and end date parameter (both nullable). It works fine if both dates are null.

But if we specify date range, the report takes 5 minutes to load and many columns data is missing..

We are not sure about the cause. Can somebody help?

Thanks in advance.

-Jai