@flaviosr
Do I have to make some particular settings in the BIOS?
You should enable "1 LUN" for the SCSI units in use. Use ESC key to enter the BPPC "BIOS".
IIRC BPPC defaults to all 7 units having LUNs enabled, but perhaps the previous owner might have had them disabled for faster startup (every unit with enabled LUN(s) is probed at startup, adding to boot time).