I am replacing a 3 wire nm100 system with a nwh300c system. Everything is working great except the door unit and chime. I have wired the black and red wires to the "door" connections and plugged the chime in where it says chime but nothing at the door works. Do I need to hook up the green wire from the door somewhere. I know the door speaker works because I wired it to a room speaker and it played music.