Both of the previous respondents have been a bit coy... 
When you can't get the transport to move, the only reason for this is that Audition isn't connected correctly to your sound device; there are no alternative explanations. So whatever it is you've done with sound device checking, and Audition settings, I'm afraid that it isn't sufficient.
It might help initially if you could post a screenshot of your Audio Hardware settings if you are continuing to experience difficulty with this. Also, do other apps play correctly?
To simplify:
Go to Windows Audio Control (right click the little loudspeaker icon on the bottom right of your screen. Select Playback Devices. Check that the device marked as default is the one you want to use. Go to the advanced tab and set the sample rate and bit depth are what you want to use. If the device you want isn't shown, right click on any white portion and make sure the options to show hidden and disabled device are ticked.
You might as well repeat the above except with Record Devices.
Next, in Audition, go to Edit/Preferences/Audio hardware and check what Device Type (Driver) is selected. As a rule ASiO is best but not all hardware supports this. Anyway, whatever is selected, change to anything else. Okay out of this screen...then go back and change it back to what you wish to use. Okay/Save again.
Unless you've discovered some new breed of problem, this should fix things.