I am a traffic controller and I got this two way radio the Motorola Talkabout T5509 and all the other T/C and the truck drivers use channel 11 to talk, They can hear me talking on it but I cant hear them?? I have it set to 11, I have played around with it but still cant hear anyone talking?? also what is the small number to the right of the channel number 11 on the screen?? thanks