TLD(0) cannot dismount drive 1, slot 22 already is full

Hello Experts,

1:- Pls let me know why am i getting this error. and pls let me know to troubleshoot it in Windows 2008 Server with 7.6 NBU. Media servers are in Solaris 10.

TLD(0) cannot dismount drive 1, slot 22 already is full?

2:- Can we run inventory and update EMM when backup is writing to tapes and backups are running?

Thanks,