1. Set the SCSI ID if the SCSI Zipdrive to 5 (with jumpers), so the S1100 will find the zipdrive automatically when powering up.
2. Set termination of the zipdrive to "off", so you can use the external SCSI connection at the same time.
3. Put the SCSI connector of the SCSI flat cable "the wrong way around" in the SCSI socket of the Akai SCSI card. (at least with my SCSI card, there are several version, also without an internal SCSI socket) . Maybe you have to remove the "bulb" on the SCSI cable.
Cheers