Hi Mahesh,
I hope that the key that you have created have issue, or you haven't imported the certificate and revocation list to correct place.
please follow the steps given here - saurav-nav.blogspot.in/.../nav-2013-r2-windows-client-web-client.html
There are for NAV 2013 R2 but applies to NAV 2013 Also.
Let me know if you get stuck somewhere.