Hi.
I think you need to terminate your drive.
As most 68 pin scsi disk need active termination on their cable.
I have some 68p scsi drives in A590 and GVP series external HD units. And all want a active termination.
Have you terminated the external port? if any?
I use rom 2.05 and 3.1 on my amigas with this setup.
Buzz