when you say you have wired to zone 3 do you mean you have connected A & B to zone 3?
you will need to program the zone. The only things i can suggest is test the relay on the detector with a meter.
Also your panel isnt in EOL configuration is it?
How are you testing it?
and where are you expecting the sound to come from, ie of the panel is programmed for double pole and correctly set up, disconnecting A or B should result in an alarm at the panel.