In the file HP-1, on the Media Agent (BMA in the session report), run
UNIX
/opt/omni/lbin/devbra -dev
Windows
cd \Program Files\Omniback\bin
devbra -dev
See if your devices show up there. If so, you may need to do some reconfiguring. If not
UNIX
ioscan -fnC tape
Windows
Device Manager -> Tape Drives
and see if your drives are there
In the file HP-2, the error could be caused by having /C as a Dynamic Disk
Look for a file on /C called 'Program', if you have it, then delete it
Other than that, this has been fixed in various versions with patches. If neither of the first two suggestions work, you should open a case with the Response Center