Deciding between System State Backup and Allcritical Backup in Windows Server 2008: Which one is the right solution for my needs? To perform a system state backup with this subcommand, you must be a member of the Backup Operators group or the Administrators group, or you must have been delegated the appropriate permissions. In addition, you must run wbadmin from an elevated command prompt. (To open an elevated command prompt, click Start, right-click Command Prompt, and then click Run as administrator.)

More info: TechNet

Source:→ Storage team blog