Hi,
1. Please check if the Backup Exec Service account has the following rights according to
Document ID: 243033
http://support.veritas.com/docs/243033
What rights must the Backup Exec Service or Logon Account have when backing up local and remote computers in a Windows 2000 and 2003 Active Directory environment, in order to back up the System State.
Also, make sure the "System Logon Account" under Network --> Logon Account - is the same as the BESA (backup Exec Service Account).
2. Make sure you have the rights to access the registry of the DC
3. Enable Restrict Anonymous Support on the backup Exec server and the Domain Controller , follow
Document ID: 238618
http://support.veritas.com/docs/238618
How to enable support for "Restrict Anonymous" when using Backup Exec 8.6, 9.x, and 10.x for Windows Servers