Cannot arm to record in multitrack

I've used Audition 2.0 extensively, and recently got version 3. I can record in the "edit" view with no problem, so everything should be set up correctly. However, if I try to arm a track to record in multi-track view, it will not let me. If I try to click on the "R", nothing happens. I don't understand what could be happening, as I had *no* trouble with 2.0

Using Windows XP, by the way.