I appear to be having the same trouble.
Bought a PCMCIA CF card reader and CF card from AmigaKit. Installed everything and it all worked fine.
One week on went to use the card and it first appeared in Workbench as a NONDOS CF0: and now doesn't appear in Workbench at all.
The card appears fine in a USB reader with Windows XP and Mac OS X. I've tried formatting it with FAT and FAT32 but fails to appear in Workbench.
Do I have a faulty card?