Server was unable to complete the requested operation

A. Logon account may not have the appropriate privileges for the selected resource.
B. The log on account uses an expired password
C: The log on account is either expired or deleted or User may not exist
Check the status of the Backup Exec Remote Agent service on the Linux server by using the below command and make sure it is running:
/etc/init.d/VRTSralus.init status
Backup Exec Remote Agent : [RUNNING]

Note: If the Backup Exec Remote Agent service not running; start the service by using the following command
/etc/init.d/VRTSralus.init start
Solution A : Make sure log on account used to connect Linux server have appropriate privileges.
The logon account specified must exist on the Linux/Unix target server and must be a member of the Backup Exec Operators (or 'beoper' ) group to perform a Backup or a Restore Operation. (This restriction applies even to the super user, or "root" account).
Note :
When you install the Linux Agent, Backup Exec creates the beoper group and adds root as a member. The beoper group contains the names of the users who have permission to back up and restore the Linux servers. However, if Backup Exec detects an NIS server during the Linux Agent installation, then the beoper group is not created. You must create the beoper group manually on the Linux servers on which you want to install the Linux Agent.
Solution B : Make sure the password is not expired
Solution C : Recreate the account in Backup Exec