Sorry for the slow reply. It took a few days before I could work on this again.
I ran a job in "Backup" and it backed up everything (73GB) with no problem. For some reason, I had to remove the drive and re-add it in hardware manager to get Backup to use it. When I did that, it loaded the Exabyte driver, rather than the Veritas driver.
After that, BE wouldn't use the tape drive, but a restart the BE services fixed that. BE shows a total and available capacity of 73.4GB. I am now in the process of erasing the tape and then I'll run a full backup in BE to see if it works like it did in "Backup." I'll post results on Wednesday.
Thanks again to everyone for your help.