The below error may occur during backup of domain controller:
"Failed to install the agent: Cannot determine the type of the target computer processor. Access is denied"
If this error occurs during both manual and scheduled backups ensure the account being used to run the backups has the correct permissions. Try mapping a drive on the DC from the RMAD server using these credentials. For more information on the permissions required, please review the below solution:
https://support.quest.com/Search/SolutionDetail.aspx?id=SOL13112
If this error only occurs during scheduled backups, verify the credentials used to run the schedule has the correct permissions. Also verify that there is only one schedule being run at a time.