Mixer won't send audio to PC

Hey guys!

I'm fairly new here but not a total newb to the Audition world. I've been using Audition for about a month with a USB to PC mic set up and just recently switched to using an audio mixer. My microphones are Behringer and the mixer is also Behringer. I received my mixer and all the new cables on Friday, Jan. 25th. As soon as it arrived I set it all up and it worked like a charm. It was great. When I was done, I unplugged everything and put it away neatly.

Two days later, today, I go back into my office and plug everything in the exact same way I had it on Friday...and Audition will not pick up any of the audio coming from my mixer. My mixer is definitely picking up sound, I can see it on the device, but my program is receiving none of it. I have been messing with settings for about an hour now and I'm pretty close to losing my entire mind.

Help!

-Chelsea