i meet an error when I using backup exec to backup

Hi All 

I get some trouble when I backup with backup exec 2010 , when a job is processing , I receive an error information

 " e0008115-The job failed with the following error: Physical Volume Library Drive or Robot paused, offline, or disabled."

and

" Robotic library hardware error.The robotic library has reported a general hardware error condition. Manual intervention, calibration, etc., may be required. This may be a device related hardware problem, or it may be some other hardware problem (i.e. SCSI card/bus etc.). The library and drive states have been set to offline. Please attend to this condition."

and since then ," all my job's status turns to "missed"  , 

My device is Quantum superloader 3 , I used to ask Quantum support for help , the Quantum engineer checked this device and they believe that the hardware did not have any problems. 

Can anyone help me to trouble shoot on this ?

Thanks