The Backup Wizard won’t write to REV drives b/c IOmega set them to look like CDs, and the Wizard looks at whatever that attribute is. NT Backup looks at the drive just fine, though. Since the Wizard actually configures NT Backup, the best workaround to allow you to use the Rev with the Wizard is:
Use the wizard to configure the backup to a hard drive, then open up regedit to:
HKLM\software\microsoft\smallbusinessserver\backup and change the key
“Backup Location Path” to the Rev Drive.