Try checking out the volume then check it back in.  I had the same problem and 
this worked for me. 

>>> fabio.diciommo.eds AT TESORO DOT IT 12/12/01 08:34AM >>>
> Hi all,
> I'm using TSM rel.4.2,STKL700 with four LTO drives.
> Recently, cartridge 000131 stuck in drive n°4, I manually removed the
> cartridge and put back in its home cell. The cartridge and drive n° 4
> aren't broken.
> When I started migration I received this message:
> 
> 
> 07/12/01 20:39:47     ANR1401W Mount request denied for volume 000131 -
> mount   
>                        failed.
> 
> 07/12/01 20:39:49     ANR1401W Mount request denied for volume 000131 -
> mount   
>                        failed.
> 
> 07/12/01 20:39:50     ANR1401W Mount request denied for volume 000131 -
> mount   
>                        failed.
> 
> 07/12/01 20:39:50     ANR1021W Migration process 21 terminated for storage
> pool 
>                        SPDFILE01 - storage media inaccessible.
> 
> 07/12/01 20:39:50     ANR0985I Process 21 for MIGRATION running in the
> 
>                        BACKGROUND completed with completion state FAILURE
> at    
>                        20:39:50.
> 
>  
> I started, "Audit Library" with the following output:  
> 
> 07/12/01 20:39:46     ANR8461I AUDIT LIBRARY process for library
> SM01TL01-XX    
>                        completed successfully.
> 
> 07/12/01 20:39:46     ANR0985I Process 20 for AUDIT LIBRARY running in the
> 
>                        BACKGROUND completed with completion state SUCCESS
> at    
>                        20:39:46. 
> 
> but when I started migration again, the result was:
> 
> ANR1401W Mount request denied for volume 000131 - mount failed.
> 
> 
> The volume never gone "unavailable". It was "read/write" all the time.
> 
> 
> How could I do to unlock this situation and recovery the volume data ?
> 
> Thanks
> Best regards
> 
> Fabio