Servos not getting powered

I can’t seem to get the servos from the PH to function.
I have the latest plane FW, 2.78b and get a solid green armed light on the PH. I can calibrate the radio and can see Ch in and outs matching via telem. I am powering the RC Rx from the PPM connection and can get servos attached directly to the RC Rx to function just fine. This would seem to indicate there is power to the 5V rail.
So it would appear either there is no signal or no power going to Ch 1,2,3,4 or no signal. The ESC will not arm as well.
Any help greatly appreciated.

Have you installed and pressed the safety button so that the LED is solid red?

After a great deal of frustration, I discovered what you just mentioned.
I was under the understanding that on “plane” you could disable the arming check, which I did. But as a last ditch effort, I installed the safety switch and all worked.

Next question: Is there a way to eliminate the need for the Safety switch? On a single engine plane, I’m clear on the value added.