Help: Windows 2008 R2 & LDAP

I have a Windows 2008R2 Domain controller and I am trying to get open fire setup. Everytime I go through the Admin setup the LDAP for Active Directory test fails with “Error authenticating with the LDAP server. Check supplied credentials.”

My AD environment has Administrator under 'users" and all the other users under “GPO Groups”.

I’ve been trying with the following settings:

Server Type: Active Directory

Host: ComputerName.CompanyName.com

Port: 389

Base DN: cn=GPO Groups; dc=CompanyName;dc=com

Administrator DN: cn=Administrator;cn=Users;dc=CompanyName;dc=com

Am I doing this wrong? Is there something in Win2008R2 that I need to configure for LDAP to work?

thanks,

change your base dn to not include the cn=GPO Groups