Help with altec Lansing octive duo?

So in December I bought this dual dock iPod speaker and right away when I put my 4.2.1 iPhone 3GS on it, it said charging is not compatible with this iPhone. So I took it off and put it back on a few times finally viola it worked. I was bumping some 2pac. I haven't tried to listen to music since until today. "charging is not compatible with this iPhone" I took it off and on multiple times and the music would play but not through the speaker, only through my phone. I downloaded both apps that it has for this product, I switched docks, turned it off and on, unplugged it, still can't play music through the speaker. Any advice?