Cant get comms window to show

For some reason I can no longer get the comms window to show up. (The one that shows when you press the ' key.)I can get the Auto-tune window (CTRL+') to show, which correctly tunes the frequency. But when I press ', to speak to ATC, no popup shows, thus I cant really say anything to them. I Checked and when I tune atis, it does scroll across the top. So the comms do appear to be working, I just am mute! I've also checked to ensure ' is assigned to the comms window in keyboard settings.If anyone could shed some light I'd appreciate it.Brad