Using Run_Report_Object() to call Reports with a parameter form

Hi,

How to use run_report_object() with parameter form set to 'yes'. I have a report called from form after the parameter form shows up once I enter the parameters and push 'submit query' button I am getting below error.

Error 500--Internal Server Error
From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:
10.5.1 500 Internal Server Error
The server encountered an unexpected condition which prevented it from fulfilling the request.

Any help would be greatly appreciated. We are migrating to 11g forms/reports

Thanks

Raghu