Note that it's "589", not "598".
Make sure you're calling CardPatch or CardReset in your Startup-sequence (or else insert the card after workbench has booted). Also ensure you don't have Squirrel SCSI interface software installed.
If you want to do a low-level test on the card, download SANAUtil from Aminet and run this in the shell:
sanautil -d 3c589.device status
