can i connect my ipod to a promethean

I have used the audio cord on the Promethean to connect to an iPhone and iPod in the past, just to play music and audio through the speakers on the board, not to show things through the projector. I am trying that again, on a different board, and it isn't working. The sound plays through the iPod just fine, but when we plug in the audio cord, the volume bar goes to max, but no sound is coming from speakers. Is there a setting on the iPod that we need to adjust? Or is it something else that I'm missing? We didn't have this trouble before. We even connected an iPhone to the speakers to use for communication during a webinar. This is something that works, I'm just not finding the fix for the problem we are having this time.