Exception in portlets

Hi, I am rajesh. I have installed webmethods 6.5.1 with SP1 including portals.While editing the portal homepage , I want to drag some portlets to the mainpage but it is giving some exception like the below one.

[POP.001.0002]A”javax.portlet.PortletException”occurred with the Message “at

Please can one help me iam new to the WebMethods.