I use a button on my CH Eclipse yoke (Button 1) for the P2A PTT function. This usually works ok. I have found a situation where if you do not have the CH Yoke turned on when you fire up P2A then there is a problem. P2A does not see the PTT button correctly.

I can go into the Config screen, then the Btns screen. It is shown there that P2A is using the CH Yoke and Btn 1 as it should. I can open the Set screen to reset the button - when it comes up, it displays the CH Yoke Btn 24 as the set button - which is not what was on the first screen. I press Button 1 on the yoke and P2A sees it and sets the Btn to 1. So P2A certainly sees my yoke and the button press. I Save then and exit, but it still does not work. ie no PTT. I can repeat this action - and it always comes up as Btn 24 in the Set screen. 

 

 

Try restarting P2A after you turn on the CH Yoke.