I was wondering if there I was doing anything wrong with regards to mic selection on the VHF comms? I have the proper freq. selected, and the ATIS bar comes up, but when I switch to clearance, I get nothing. This is even with the receiver turned up, the mic light on, and the green LED illuminated. I do used Pro ATC X.

You need to set up a keystroke to COM 1 transmit, then you need to push this option before requesting clearance. This is the only time you will be required to do this, at all other times you will be able to use ProATX as normal.