I'm trying to set a backup to tape of a machine using flexbackup. However any attempt to write to the tape drive (via either flexbackup or just tar) results in "/dev/st0: Input/output error"

The machine seems to recognise the drive ( HP Storageworks Ultrium 448 ) and that there's a tape in it and "mt status" seems to work... "mt -f /dev/st0 rewind" or "erase" throw no errors...

Code:
root@stor001:/# mt status
SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x42 (LTO-2).
Soft error count since last status=0
General status bits on (41010000):
 BOT ONLINE IM_REP_EN

root@stor001:/# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: HL-DT-ST Model: DVDRAM GSA-4084N Rev: KS02
  Type:   CD-ROM                           ANSI  SCSI revision: 05
Host: scsi2 Channel: 00 Id: 03 Lun: 00
  Vendor: HP       Model: Ultrium 2-SCSI   Rev: S65D
  Type:   Sequential-Access                ANSI  SCSI revision: 03
"tell" does however

Code:
root@stor001:/# mt -f /dev/st0 tell
/dev/st0: Input/output error
Based on a forum post I found elsewhere, I tried:

Code:
root@stor001:/# dd if=/dev/zero of=/dev/nst0 bs=1024 count=10
10+0 records in
10+0 records out
10240 bytes (10 kB) copied, 5.0815 s, 2.0 kB/s
which gave the person on the forum an error but seems to work for me.

If anyone has any suggestions, I'd appreciate it