macbook pro to stereo wired

[rglmac]

I cannot get my macbook to play through my stereo. I play my I phone on the same auxillary hook up. the stereo is on auxillary the headphones work on the macbook and the macbook internal speakers shut off when the head phones are plugged in.


When I hook up the same plug that works for my I-phone the macbook internal speakers continue to play and I get no sound to my stereo. So what is going on in the Macbook

Thanks RGL