Data Protector Express sees only cleaning tapes on library

[Rod Johnson]

I have a C5713A internal 40x6 DDR-4 autoloader, which I have been using with NTBackup on a small home office network (1 file/internet/tape server, 4 workstations, all running Windows XP Professional). I have just downloaded and installed an evaluation copy of Data Protector Express. However, whatever tapes I load into the cartridge, Data Protector Express only reports finding 6 cleaning cartridges. I have tried new tapes, reformatted tapes, used tapes. All the used tapes I have tried work fine with NTBackup (to the extent that NTBackup works at all), and pass the read/write test in the autoloader drive on HP L&TT. I also have a single DDS-4 drive which has no problem with any of the tapes.

What can be going wrong?