backup difficulties

[Shawn Koppenhoefer]

  DUMP: Date of this level 9 dump: Mon Jan  7 12:00:02 1991
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping /u/giraud to /dev/rst8
  DUMP: bad sblock magic number
  DUMP: The ENTIRE dump is aborted.


When I to a "dump f /dev/rst8 /u/username "
I get the above error message. What's my problem?
An mt -f /dev/rst8 status yields the following:

   Wangtek QIC-150 tape drive:
      sense key(0x0)= no sense   residual= 0   retries= 0
      file no= 0   block no= 0



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