Backup Exec 9.1 won't write 2nd time to new tape 1

[MacGyverNeedsHelp]

Was having problems with old tape drive that new tapes did not resolve. Installed new tape drive, then new scsi card, then new cable. Bought another new box of Compaq tapes, which the system finally recorded on. When it came time to overwrite on these tapes, the program says it is bad media. The media set is overwritable with infinite append. Are these just junk tapes or am I missing something else.

 

[JoeJTaylor]

are the tapes themselves write protected? if they all worked first time then its very unlikely they're all duff tapes and the fact that they were written on casts doubt that its any of the physical hardware

 

[MacGyverNeedsHelp]

Thanks JoeT. I took one of the tapes, manually switched the write protect on tape, and received a write-protect notice when attempting a backup. Manually switched the tape back, and received a bad-media message when attempting a backup.
I tried to erase a tape, inventory a tape, and nothing seems to reset the tape to where it is reuseable.