I have had problems with ambient sounds not playing at all. Has anyone else encountered this?
Please give more details: Are there some specific situations where none of your ambient sounds play (have you tried other files as well?) or is it specific files that don't work? If so, have you tried playing these sounds normally with the PlaySound function to see if they work at all?
So are you sure it's not the sound files themselves? What file format do your files have? For example, remember that AGS only supports uncompressed PCM wave files.