You probably have to program the buttons - that's what I had to do for my mouse.
Go to: Star menu -> Settings -> Control Panel -> then open up the file "Mouse" -> it should have your regular buttons (Left button: ___, Right button: ___, Wheel Button: ___,) and then it should have all your new "fancy" buttons
My mouse only has one extra button, so I go to the drop down box and select "Keystroke" then you need to put in a combination of keystrokes (I did alt+9)
then in wow, go to your keybindings, and you have to set the button to (in my case) alt+9, then when ever you use the button on your mouse, it acts as though you pressed alt+9
I highly suggest you use a combination of awkward keys (don't use stuff you already have hotkeyed)
hope this helps :3