Dear
Are you able to see the tape device in SQL Management Studio? if so try to create a dummy database and try to backup.
Uninstall and update the tape drivers on the production server and then check whether you are able to backup.
check the space which assign to tape device normally it could be the problem normally we assign space 400gb
in initial stage but later the prd space increasing and you might face that issue check your init.SID.SAP for space issue
Regards,