I recently moved into a new house and I hooked up my DVD player, but the picture won't show up. All I hear is the sound. I didn't have this problem at my other house, but since I got a cable box, the outlets which I plugged the other one into are being used by the cable box. I've tried plugging the cables into the other AV outlets but still no picture on my TV, which is also a magnavox. What am I doing wrong?