Thread:Extension talk:LDAP Authentication/Active Directory Group based login restrictions

Hi I have been using Mediawiki for the past 4 months with Active directory integrated LDAP logins. Now every user in AD has access to all pages once they login. My requirement is to make Group based logins and restric all other users not to access mediawiki. For this, i have added the following in localsettings.php file which is not working. After adding the last line related to Required groups, it says incorrect user name and password. Please help.