Razer Taipan Hotkey question?

I have the Razer Taipan mouse, and I have been trying to make my level up spell easier to do. This mouse has 2 buttons on each side, with these buttons I wanted to make my level up something like this. MB4 + Q. But for some reason whenever I try to enter both of those bottons, only one of them comes up, like MB4, or just Q. Point being, I want to know if there is a way to have this combination for the hotkey.

Thanks!