Not sure whether I've understood your scenario completely. You have a standalone drive and variety of tapes to which you wrote the data. Once the data was written and tapes got offline, you moved them to "Free" media pool. Then, you tried to insert one of these tapes to the drive, and got the "Unrecognized tape" message, right?
Also, are you aware that moving tapes from one to another media pool marks tapes as free and, therefore, the previously written data will be eventually lost
. So, what is the reason of moving all
tapes to "Free" media pool?