no audio on DVD after encoding mpeg with mainconcept

Hi, I have an audio problem that I hope someone can help me with. I’ve editited a short film in AVID Xpress Pro and made a Quicktime reference file which I’ve brought in to Mainconcept Mpeg Encoder 1.4.2. I’ve then encoded a DVD mpeg that I bring into DVDit. I have perfect sound and picture all through this process, but when I make a DVD there’s no sound. At a forum I found on the internet I was told to set multiplexing to “none” in the advanced meny, but I’m not able to. Any ideas?

Danny Boy