you won't hear as much air traffic with the 800 MHZ antenna as you might with antenna that is better equipped to pick up air, such as the Diamond RH-77 or similar.
I put my Pro-164 side by side with the same Air freq. The Pro had no problem.
I switched the 436 to the RS 800 MHz antenna same deal. I am not picking up any air communications
What is squelch 2? is that on the 436?
Do you have the proper "Service Type" enabled for the frequencies you are trying to monitor?