the package says usb-ready, osx compatible and plug and play, but it doesn't work.

Support Information:
Device Type: Input Devices (mouse, etc.)
Manufacturer: Okion
Model: KP118U Keynotes USB Numeric Keypad
Interface: USB
Operating System: MacOSX
Age of Device: < 6 months old
FCCID:

Find it on DriverGuide (http://members.driverguide.com/index.php?action=srch&sm=b&aax=&qa6=&qa5=9&qa7=2200&dp=0.5&qm0=KP118U+Keynotes+USB+Numeric+Keypad&jmd=and&fzz=d) | Find it with Google (http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=Okion+Input+Devices+%28mouse%2C+etc.%29+Okion+KP 118U+Keynotes+USB+Numeric+Keypad+MacOSX+)