Brian,
You should be able to connect all 3 wii cables to the wallbox, to get sound and video. The wallbox has a video cable that goes to the projector for video. You will want to ensure that the video cable is connected to the projector. If so, it could be possible that the wallbox is defective. Please contact Technical Support via the web form on the knowledge base at www.prometheankb.com, select your region/language, Interactive Displays, Contact Us. In the Existing case field input case number:258020 and provide the ActivBoard's serial number.
Thanks!