No signal at night

What you are hearing during the day must be what is called "skip". Skip is active during the day where you will hear radio operators from hundreds of miles away. Their signal is bouncing off an atmospheric layer well aboe the earth's surface. At night this atmospheric layer degrades and then so does the skip. Unless there is someone close to your vicinity transmitting on the channel you are listening too, you will not hear much at all. Try changing the channels until you pick up a conversation.