As we all know, Symantec Backup Exec 2010 r2 Locks door of Library when a job is started and never release it:) so you have to start unlock library job on Devices Tab in Symantec Backup Exec 2010 r2 Console even you do not near of your Symantc Backup Exec 2010 r2 server console but you have to do it.
Anyway Symantec provide a option which is disable this behavior.
We’ll just replace a value in Register key. Go“HKLMsoftwareSymantecBackup Exec for WindowsAdamm” and replace “Disable Library Door Lock” value “0” to “1“, after restart Symantec Backup Exec 2010 r2 Its done.
Maybe you should restart your Library. (Depends on Library model) ….