Adobe after effects no volume after save?

I make movies with high effects. I make them with adobe after effects. The problem is that when im making the movie i can hear the sound with the RAM preview but after i publish it to an AVI or other video file it has no sound. Ive tried using sound on other programs and they work. Its just that after saving they are muted nomatter what! Please help :) Thanks! :) Please be descriptive. I have CS4 and im running windows 7 if it matters