Backup location cannot be accessed

I am using Vista Premium booted from an NVIDIA (mobo chipset) Stripped RAID
drive (C based on two SATA drives. I also have an IDE drive (D, which I
use to perform backups to. Before I built the RAID volume, one of the SATA
drives was a plain boot disk(C and the 2nd SATA was absent (or unformatted)
and the IDE drive (D was configured in the Windows “Backup Status and
Configuration� section of the “Backup and Restore Center� as the location to
which to “save your backup�. This was used successfully a few times, but
since I loaded the NVIDIA RAID drivers and built the RAID volume, Windows
Backup will not allow the IDE drive to be selected as a location and any
attempt to perform a backup now results in the message: “The backup did not
complete successfully. An error occurred. The following information might
help you resolve the error: The backup location cannot be accessed. Review
your backup and restore settings and check your hardware configuration.
(0x81000002)�. I did not reinstall Vista when I built the RAID. Instead I
part enabled the firmware and booted from the existing JBOD. Then I
installed all the drivers and checked it all worked, before backing up the
partition (offline using Paragon’s Drive Backup Recovery CD) and restoring
the partition to the newly constructed RAID volume. Vista boots fine and
I’ve had no other issues but this. The IDE drive (still D is otherwise
functioning just fine. Why does "Backup Status and Configuration" not see
the D: Drive?