What rights does the Backup Exec service account need?
If this computer is in a domain, enter a Domain Administrators account, or an equivalent account that is part of the Domain Admins group. In the Domain list, select or enter the Domain name.
If this computer is in a workgroup, enter an Administrators account, or an equivalent account that is part of the Administrators group on the computer. In the Domain list, select or enter the computer name.
Note: Due to security implementations in Microsoft Small Business Server, the service account must be Administrator.
Act as part of the operating system (Windows 2000 only)
Backup files and directories
Create a token object
Logon as a batch job (Windows 2008 and higher)
Logon as a service
Manage auditing and security log
Restore files and directories
Take ownership of files and other objects
Note: "Create a token object" right is not required in Backup Exec 2014 and higher.
Also make sure the account is not added under:
Deny logon as a service
Deny logon as a batch
This is important because the DENY takes precedence over allow.
The account should have its Primary role as Domain Admin in Active Directory.
Please contact your local server administrator to configure above mentioned rights or refer below given Microsoft website :
Please review http://www.veritas.com/docs/000007290 for other rights required for each Agent / Option being used in Backup Exec.