Marcelo -

Use Query PRocess and Query SEssion Format=Detailed to see if the
tape/drive is actually in use, and Query Request to see if an
associated tape is needed.

A situation which goes on for days, as you have encountered, is
abnormal, and may indicate that a tape mount is actually not
completing, and that can be due to a drive defect or even a tape
already in the drive (stuck there, after a previous dismount failed).
Inspect the drive for problems. Depending upon your drive type, a
Reset or power cycle may clear its condition. But thereafter keep an
eye on the drive for further problems, where a technician would have
to work on it.

   Richard Sims