yeh that box is only used on early cars with cable throttle.
If you have DBW and the cruise info is appearing in the ECU, you dont have one of those boxes.
You can check the status of the switch and pedal inputs in VCDS and see from there whats going on. If its not working its usually either a faulty stalk (when they wear out the contacts start getting dicky and you can see the binary digits flickering on and off in VCDS) or, something silly like your driving along with your foot resting on the clutch pedal.
