Hi All,
After doing some investigation in Auth.php file, I found that the encoding conversion for the username was returning blank value. So, I re verified my LDAP settings for the encoding and realized that there was typo error that I had done while entering "utf-8" value (I had enetered 'ulf-8', silly me!!) .
Once I fixed this typo SSO is working as expected.
Thanks You!!
-Rajiv