backup job cancells on its own

I'm using brightstor arcserve backup r11 for netware. I'm using a tape library with two jobs scheduled. The first runs, then the second which is for groupwise 7 cancells saying a user cancelled the job but, thats not true. Any help or advice would be apreciated.

All I can think of is the needed tape was not available which resulted in the timeout and the status of canceled by user.