Yesterday night I was trying to test some ascx control having ReportViewer control in it. By the way I had developed the controls several days ago for one of my client and it was working then. But in the mean time I have reinstalled SharePoint again and now after deploying the control with SharePoint it was not working . I had surprised of what the issue is......... The same PC, server and SharePoint.
Later I have found that to run RDLC report session state need to be enabled. And this could be done from web.config by uncommenting the following line
<add name="Session" type="System.Web.SessionState.SessionStateModule" />
Also you need to enable session state by setting the property true.
And finally it worked.