@Vinod_Yadav ...Chris and Guenter bring up good points. First off, lets start with basics...when you say thin client, what exactly do you mean? Only thin client I ever know when it comes to CP is whats called SSL network extender (SNX) and that goes through the web browser, so there is no need to install the actual VPN client. Now, it would definitely help us if you could clarify things we mentioned AND also provide us with screenshot of the logs and what exactly you excluded.
If you can give those, Im fairly certain we would be able to point you in the right direction.
Cheers,
Andy