Wacom Graphire 3 not working, Pixelmator

I have an old Wacom Graphire 3 pen tablet with a usb connection. I plug it into my Macbook Air and it moves the cursor around, but there is no pressure sensitivity in Pixelmator. Also, the Wacom section of the System Preferences says it cannot see any wacom hardware plugged in. But there is definitely a Graphire 3 plugged in.

I downloaded and installed the Wacom package for this OSX but it is still not working. Does anyone have any suggestions? Thanks.