I get an error message when I use the dump command to backup files to tape. How do I backup files to tape drive?

When a user tries to use the dump command for backup from /mnt/backup/ to /dev/st0 (the tape drive), the following type of error message may result:

#/sbin/dump -0u -f /dev/st0 /mnt/backup/
  DUMP: You can't update the dumpdates file when dumping a subdirectory
  DUMP: The ENTIRE dump is aborted

The problem is that a tape dr...