Question about headphone jacks

[Delirium]

I enjoy putting my phone MP3s through my sound system and even through my computer via the audio in option. Unfortunately, (even with my new phone) it doesn't work properly with some connections. For example, I have a red and white stereo cable which convergences to a headphone jack (3.5).

What am I doing wrong? My phone (even my brand new one) doesn't recognize it is plugged into a headphone jack unless it is a stand alone headphone. Does anyone have any ideas?

Thank you in advance!

[Dark]

What phone is it? And are you having a problem with a home theater receiver or a stereo receiver? Or running it through the computer.  Guess what I mean is exactly what connection type and to what source is the problem area.

For my setup.
    
Phone head Jack to stereo receiver via splitter (red/white) plugged into CD port
phone with splitter to home theater (red/white) to auxiliary Jack
Phone to computer via straight headphone line to mic port
And make sure to select right input on receiver

Now if I have music playing and try to connect to anything nothing will happen till I shut down the music player and restart it. And if I try a different port on my home theater receiver other then the auxiliary one it doesn't want to work. Oh one more thing atleast on mine if you are not playing from built in music player it doesn't work either and volume on the phone has to be turned on. Did that once and couldn't figure out for almost an hour on why no music lol

Original Droid
stereo (old RCA )
Sony 7.1 HT

[Bizman]

What phone is it?

Now that is ultimately the best question to start with. 

My guess is, that your phone might be using a four-section plug (tip-ring-ring-sleeve) to be used with a headset including a microphone. iPhones use that, I don't know about other brands. Computers use the standard stereo jack-plug system (tip-ring-sleeve) for all jacks.

[zack1234]

(tip-ring-sleeve) 

I am easily pleased

[Bizman]

(tip-ring-sleeve) 

I am easily pleased

Glad that I be of help in lightening your daily burden.   

[bustr]

Does an adaptor exist?