NIPAP, AD authentication

[amizeromir]

dear all,
I have a fresh NIPAP where the default_backbend is set to local. I would like to set the AD authentication so that users in a OU called Super User can log on the app with their AD SU accounts . a security group is also created on the AD where those users are listed..
I edited nipap.conf but still I m getting invalid username or Password.
BUt when I do an ldapsearch on the console I get result
need your support , dont have much experience with NIPAP