I've got a couple places in town with a stray KA false. I've read the manual 5 times and tried everything I can and I can't seem to mark them so they auto mute for next time. The instructions say to push the mute button and then push it a second time while "Mute On" is displayed. When I do that it just turns the mute off instead of marking that spot for auto mute. I've tried pushing it faster, slower, longer, etc... and nothing seems to work. I feel like I must be missing something obvious. Any thoughts? Will it not lock out KA signals at all?