You are trying to get sound from the TV to the Beosound, right?
Are you sure you have the right adaptor? If it has two pairs of phono plugs, I believe you should use the ones labelled OUT... If it only got one pair, try to connect it to an input on your TV, and play a CD... If you get sound on the TV, it's the wrong adaptor...
5 pins or 7 pins don’t matter...