4mm DDS backup greyed out under Microsoft Backup Restore

I have created two backups of Windows 2000 Advanced Server, one full
and one incremental, using Microsoft Backup Version 5 on a SONY
TSL-9000 managed by Removable Storage. I made copies of both
C:\WINNT\System32\Ntmsdata and C:\WINNT\System32\Remotestorage, and
then reinstalled Advanced Server. C:\WINNT\System32\Ntmsdata and
C:\WINNT\System32\Remotestorage were copied back onto the system.
Everything appears fine under Removable Storage, with the backups
appearing under Removable Storage -> Media Pools -> Backup -> 4mm DDs,
and SONY TSL-9000 appearing under Physical Locations.

However, under the Restore tab in Microsoft Backup, the two backups
appear under 4mm DDS, but they are grayed out. How can I make them
availible for restoration?

Thank you,
Rob Mosher

P.S. Unfortunately buying superior backup software isn't an option.