Wireless RADIUS Authentication ERROR

Hi there,

I'm working on a project that requires me and my team to setup RADIUS server to which allows users to Join Wireless AP using their Active Directory credentials, we have options to do either on Server 2008R2 enterprise or Server 2012 standard.

I followed this video

http://www.youtube.com/watch?v=PjdFwQc_tCw

and configured our whole network, but when wireless client try to authenticate, it shows its processing but fails after few seconds.

Please Help me in solving this issue... URGENT PLZ

Thanks,

HIMANSHU