Dear Raj,
The information you provide is not enough to discover the problem.
I would like to recommend you this SAP Note: 1332726 - Troubleshooting Wizard, where you will be able to find information how to use the diagnostic tool for collecting traces and to discover what could be wrong with your setup.
Also you can use this document Secure Login for SAP NetWeaver Single Sign-On Implementation Guide Chapter 6 Troubleshooting.
Here you will be able to find a lot of content about the SAP NetWeaver SSO implementation and setup: http://scn.sap.com/community/netweaver-sso
I hope this will help you to find and fix the problem.
Kind regards,
Donka Dimitrova