I bought the cable to hook my Macbook to my Sony Bravia TV. I am in the 3rd port from the back on the Macbook. I also have another cable hooked up from the headphone jack to the RCA connection under the computer connection on the back of the TV. All I get on the TV is the wallpaper from the Macbook. I have the TV set to the right input chanel and the Macbook works like it always does, it just does not translate to the TV. What am I doing wrong?