I wanted to try the IFX setting on a channel (TG) but when I press "FUNC then "7" there is no indication in the display that it is ON or OFF. I am using detailed trunk display mode. I just get 3 rapid beeps when I do "func" then "7" like an error. I sdet in display at bottom left of screen the IFX text to be yellow. How do you tell if it is on or off?