No sound from powered external speakers SG2 thinks the speakers are headphones!!!

I'd like to use an external speaker(s) to play internet radio out loud from S Galaxy S2. The phone's speaker works fine, radio plays out loud from phone's speaker. THE PROBLEM: when i plug in speakers to the headphone jack, the phone reads it as headphones - no sound comes out! The speakers are good, phone works w headphones so seems like the jack is fine. I've tried additional speakers too. They all have been small computer speakers w external power source. I have soundabout app on phone - still in trial but willing to pay for app - but played w settings, still NO SOUND from speakers. Suggestions much appreciated!!

I think its great that the developer of the SoundAbout app takes the time and effort to answer questions....  with that in mind....It's so frustrating to see that my question (and 2 others) were skipped over with no clue as to why.  If the answer is obvious, I apologize, i really HAVE made an effort to sort it out on my own but no luck..  THANK YOU.

Still hoping I can use my phone to play music through some type of speakers in my studio.... awfully silent in there.   

Are the speakers getting power? The phone will not be able to use external speakers unless they are powered and plugged in. The phone only has the ability to work with small speaker,like headphones that are not connected too a power source.

I've also heard of people using a cable like this to send audio to a receiver that is hooked up to speakers:

http://www.amazon.com/3-5mm-Mini-Plug-Computer-Stereo/dp/B000LMFS7M

Also, sometimes the pin alignment for the 3.5mm cable that is plugged into the headset jack is not fully compatible.

http://forums.androidcentral.com/samsung-galaxy-s3/189523-final-soultion-why-most-headsets-wont-work.html