The "R" button enables the track to record. You need to select the microphone button to record audio. Here's a quick tutorial Colin Smith made
Thank you, but there's no response from either button. I also tried the Audio Midi Setup as you suggested. I can go to Voice-Over Record Settings and see the microphone level respond (although the "Inputs" box has a triangle, but nothing listed, which seems odd). I have the new Mac Pro (trash can) which has it's oddities, and am running OS 10.9.5.
Can you get the built in microphone to work as a test?
I don't believe there is such a thing on the Mac Pro (trash can), but I did finally get something to work with a not-very-instinctive combination of System Preferences (select USB mic), Audio MiDi Setup (select USB mic), and Premier Pro Preferences, Audio Hardware (DO NOT select the USB mic, but rather the System Default Input/Output). No other combination worked (I tried them all), and when I tried changing Audio MiDi settings while Premier Pro was running, I'd occasionally get the endless spinning wheel that required a re-start. Even with all this, one channel was peaked-out with noise (source?) which I couldn't eliminate with any settings (can do it in post, however). Overall a disappointing experience. I don't know why the Audio MiDi Setup has to be involved, or why this was so difficult with my set-up (I'm not ruling out user error).
Any further advice is more than welcome,
I am having this same problem. Mac Pro, premier CC, the mic is a usb by Editors Keys. Can't enable track either by clicking mic icon in the timeline or clicking R in the audio track mixer. Incredibly frustrating. Can't get built-in mic to work either. I have watched the Colin Smith video - didn't help. It this some mono/stereo issue. My timeline is all mono.