Ipod Nano won't play through port speakers..?

Hello,
I have an Ipod Nano which has recently stopped playing through the speakers of the Ipod docking speakers. Headphones work fine but when I dock it to play through the speakers it will only play through the tiny internal speakers of the Ipod, which doesn't really fill the loungeroom. Anyone know what I can do to fix this? I've turned it off and tried again. I've synched it. Am at a loss.
Cheers.