Pb with HP DAT and Adaptec Future Domain

Hi everybody...
I've been using linux for a while but I'm experiencing troubles using my DAT. It is a HP 35470A (rev T603) connected to an Adaptec AHA 2920.
It is normally recognised during boot, but when I issue the command
tar cvf /dev/rmt0 /
the Dat begins working, but after a while it locks up and I get the
message
# scsi : aborting command due to timeout : pid 4031, scsi0, channel 0,
id 3, lun 0 Write (6) 00 00 28 00 00
fdomain: abort
Future Domain TMC-16x0 SCSI driver, version 5.44
scsi0 <fdomain>: BIOS version 3.?. at 0xc8000 using scsi id 7
scsi0 <fdomain>: TMC-36C70 (PCI bus) chip at 0x6000 irq 10
other (8), target = 3 cmnd = 0x0a pieces = 0 size = 10240
sent_command = 6, have_data_in = -1, timeout = 50
in_interrupt_flag = 0
IMR = 0x18f0, IRR = 0x0000, ISR = 0x0000
SCSI Status      = 0x01
TMC Status       = 0xf0 (interrupt)
Interrupt Status = 0x98 (enabled)
FIFO Status      = 0x08
Int. Condition   = 0x00
Configuration 1  = 0x85
Configuration 2  = 0x03

I've tried recompiling the kernel for using future domain chipset in SCSI kernel, but it hasn't changed anything...  Does anybody have the same problem ????
I've never used a DAT on linux before... Maybe, I made an error somewhere ...
Any help or advice would be great...
Thank You