1. Make sure you have a (EOL) resitor on the curcuit, it should be at the switch, but you can cheet and have it at the panel, but if your wire would ever get damaged you would not know about it 2. If you had to hammer in the switch it could have damaged the switch to a closed state and wont open when the door opens, the switch should just be pushed in not hammered 3.If the switch is installed to close to a magnet wheather stripe, that will hold the switch close 4. If it is a steel door and steel frame, and the switch is a surface switch with screw terminals, you could have some stray wires shorting to the steel frame 5. make sure your magnet is lined up with the switch