Playback in Sibelius

I have my macbook hooked up to a m-audio recording device and then to an amp and a set of speakers and I am having trouble getting sibelius(5.2) to play back through the m-audio device,(the little intro music plays back through the m-audio device but everything else comes through the computer speakers. I've tried changing the playback devices, but the recording unit does not show up, I've never had any trouble with other programs not recognizing it(reason and logic express). any thoughts/ideas?

Not to be too obvious, but it sounds like a sibelius issue. You might try giving them a call...
Might be an issue of your device being compatible.