Actually, you have it a bit backwards. You can pan mono tracks but not stereo ones (since, with a stereo recording, Audition assumes the stereo image is fixed).
A couple things to make sure of:
-Panning only works in multitrack view.
-The output for your multitrack session has to be set to stereo
Once you're in multitrack with a stereo output, there are several ways you can pan your track:
-You can use the pan control in the header at the left end of each track in multitrack
-You can use the pan control on the mixer view
-You can use the pan envelope control on the track itself in MT view--useful if you want to programme in a move as part of the mix.
Hope this helps.
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