Hello Jack,
Thank you for posting your question to the online forum.
It sounds as though Backup Exec might not be identifying your drive's media type correctly.
On the Devices tab, right click on the tape drive and select Properties. Looking at the general tab, see what is listed next to "Media type:" and Product ID:.
If the product ID shows up correctly and the media type does not match, then install the latest drivers for Backup Exec.
Installing the latest drivers for Backup Exec can be accomplished by running LiveUpdate from the tools menu.
You can also download and install them manually by looking up the drivers based on the build of Backup Exec you have installed here:
http://support.veritas.com/docs/288039 (7170 x64)
http://support.veritas.com/docs/288038 (7170 x32)
http://support.veritas.com/docs/286764 (6235 x64)
http://support.veritas.com/docs/286763 (6235 x32)