It has been a very long time since I had to do this, but I sort of remember how to get it working...
You have to make sure that the Zip and the ASR are set to the same scsi ID number.
The ASR can be set from command system menu and the zip should have a little switch on the back.
To make things nice and easy I format my main zip disk with the asr os and save all my samples for a project on one disk which is then always ready when I turn the ASR on.