Hi,

I think you should follow below given link first and then start thinking what steps you have missed in your set up and correct them. 

<https://fedorahosted.org/sssd/wiki/Configuring%20sssd%20to%20authenticate%20with%20a%20Windows%202008%20Domain%20Server>
<http://www.chriscowley.me.uk/blog/2013/12/16/integrating-rhel-with-active-directory/>


--Regards
Ashishkumar S. Yadav