Couldn't tell you - nowhere near enough information here, I'm afraid. Is Audition's transport actually moving? If it isn't, then you don't have a legitimate audio device connected to it - go to Preferences>Hardware and make sure that you can see your Behringer listed as available. If you have it connected, but just can't hear it, then you need to be looking at the mixer itself - having made sure that you are actually routing a track, or the mixer, to it.
Thanks for the information. I should have realized to check the "preferences - hardware". It works fine.
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