HELP! Everytime I do a mixdown with an "Entire Session" the file will only contain the music bed!

I suspect that Steve is correct in asking to see what the Mixer settings are or to show the Track headers with the output routing of each track. Your mix down of all tracks will only work successfully if all Tracks are routed to the Master output. Any tracks only routed directly to your soundcard and not the Master won't be included in the mix.