Razer DeathAdder Mouse back button doesn't work

I got the new Air (Intel i5 1.3Ghz) and it came with OSX 10.8. Right now it is updated to 10.8.4.

I connected my Razer DeathAdder 3.5G mouse and the back button does not work. I downloaded the correct driver from Razer and I tried to customize it but it only allows me to set the back button as "button 4" and the forward button as "button 5." According to the Razer website FAQ, these settings are recognized on windows as back/forward and that if you want to use these buttons on OSX, you must set the "button 4" as back. It reccomends that I go into the System Preference > Mouse and change the settings.

Unfortunatly in the Mouse settings, there is only Tracking Speed, Double-Click Speed, Scrolling Speed, and Primary Mouse Button.

Does anybody have ANY idea how I can get the two buttons to do back and forward? At the moment, both back and forward buttons just open links in a new tab.

Cheers

ahan88