...and you don't have any SCSI ID clashes? Try changing the SCSI ID, and if you can check your SCSI cable and termination, do that too, it at least eliminates the obvious, and what the error is complaining about.
Atari Falcon 14mb, 68882, Dual 8gb CF, Steinberg FDI & Analog 8
Atari Jaguar, Rotary controller, Skunkboard & Cat Box
Atari 520STFM 4mb, TOS 2.06 switcher, OverScan, GigaFile, PARCP-USB, Unicorn-USB, System Solutions MiniS HD, SyQuest drives, ICD Link II, PhatBoy MIDI Controller, Philip Rees 5M MIDI merge box, SoundPool MO4, Steinberg MIDEX, SMP II, Emagic Log 3, C-Lab Unitor 2, Combiner & Export expanders