Hello Marianne,
Thanks for the support first.
Second, we actually replaced the media server, and we migrated all the the tape drives to the new one.
ONce done, we triggered backup operation test but not all the drives worked correctly.
After that we requested from Oracle to replace all the tape drives which are not working and one we replaced all of them are working Idle till the moment. The problem took too much time to get resolved, since all the parts were coming from Oracle germany.
At the moment, the TL and all the drives are working fine without any single error.
Thanks all again. :)