Fix the selector PC Audio, to TX from PC Audio when use the physical PTT port of FLEX-8600

I have a FLEX-8600 radio and I use it with a computer and a USB headset connected to the PC. For convenience i use a foot PTT connected directly to the radio, using the keyboard/mouse to click MOX is slow and complicated.

But even if i change the audio selector to PC, the radio only transmits through the physical MIC the radio always TX the audio from MIC Port if push the PTT port physical.
Ever TX MIC Audio if push the PTT PORT, not the selected PC audio.

Could you add that if i select the PC software the audio is from the PC
even if i use the physical PTT of the FLEX-8600 radio?
thanks in advanced