H4n USB not recognized on mac

[prefontaine]

I have a new H4n. I want to transfer files to my mac using the USB > storage function but my mac does not recognize the USB device. I've followed the manual's instructions several times and also searched all over the web -- no luck. Below are the specifications.

Mac OS X
10.5.8
Intel Core 2 Duo

Zoom H4n
version 1.40​

Any suggestions much appreciated. I'm about to give up and just go buy a card reader. Grrrrr....