Unable to boot Solaris from external scsi cd drive on a Sun Blade 150

I am trying to boot Solaris 8 from external scsi CD-ROM drive Yamaha 8/8/24 on a Sun blade 150 through Open Boot. Its scsi ID is set to 6. probe-scsi-all reports that the CD drive is at: /pci@1f,0/pci@5/scsi@1 target 6, unit 0. So I am trying to boot with this command: boot /pci@1f,0/pci@5/scsi@1/disk@6,0 But it just halts until I switch off the external scsi CD drive. Then it fails with an error. The CD drive does not give any read indication during the entire time. The Solaris cd and the CD drive are OK I think, I only have some doubts about the scsi cable. Is this the correct command to boot in my case? Maybe the Yamaha is not compatible with the Sun hardware?