I don't know what is the problem. I am using latest version of this theme with latest version of wordpress. The favicon is appearing in the admin panel, but it's not appearing in my site.

Any help??

Site: http://biswajitdey.com

Try changing to a different favicon and see if that shows. If it does switch back to the one you were using. I have at times had some issues with favicons especially if I added a new one with the same name as an old one.