If you are not sure what the DN for the user object is, follow
this procedure from the Active Directory Services domain controller.
Procedure
At the command prompt, run the csvde -f command against the Users domain and save the output to a file (csvde -ffile.csv).
Open the file with a text editor or a spreadsheet program
and locate the appropriate user object (which can be the Full Name,
Display Name, or User logon name on the Active Directory User Properties
dialog).
Copy the DN for the user object, and paste it into User
DN for Query Authentication field in the AE Services Management Console.