My nexus works just fine. You may have it hooked up wrong. As I remember I had to remove the 4 pin plug on the tornado and install a 3 pin plug so that it could connect to the nexus. If you have done everything right and it doesn't work send it back for another one.
BTW a rheobus is a set of rheostates mounted on a plate that can be installed in your computer. Think of the bus part as a electrical bus with multiple connections hooked to it. The nexus is consididered a multi function panel because it does several things ie; controls fan speed, monitors multi temps and monitors fan rpm.
BTW again, I realllly like the nexus. It works great and looks sweet.