WinAVI 8 - .mp4 to avi conversion NO SOUND

Hi

I have an mp4 video file that I need converted to avi. When I try either divx or xvid output formats I get the following message:

Well I went ahead with the conversion and the video came out beatifully, but no sound. Am I just missing a codec? I see a bunch of options under advanced that lets me choose a sound decoder but I figured I ask someone here first, since I'm new to this particular program. Thanks for any input.

px

 

FWIW, I DO get sound and no warning message decoding from .wmv to .avi. Hmmmmm.

 

Any ideas? TIA