Cannot enable AD Authentication

Cannot enable AD Authentication

I have Service Desk Plus installed on Windows 2012 R2 and when I enable Active Directory authentication, I get an error ( User:administrator trying to enable Active Directory Authentication ) in the Support\System Log. 

I have reinstalled the application, and I can import users and assets, but the logins for Domain Users is not working. 

Can you help?

                  New to ADSelfService Plus?