Did you perhaps wire the alarm in series with the light instead of in parallel with it? If it's in series, the light will work but be a little dim and the alarm will not work. It does this because the current flow is limited by the item that uses the least current. That doesn't leave enough current to operate the buzzer. Wire them in parallel and the circuit will flow enough current for both devices, assuming that you have enough current available from the fuse and the switch will flow enough current for the ground.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
John USYacht 27 "Cora Lee"