I think your switch is screwed up.
A multimeter would be handy. Put it in continuity mode and check every pin combination and what it does when the switch is depressed vs. not depressed. Use whatever combination gives the switch as open (no continuity) if not depressed and closed (continuity) when pressed. If there are no two pins that show this behavior the switch is screwed.
Tact switches can be had for four cents each. You should own > 100 of them.
http://www.taydaelectronics.com/electromechanical/switches-key-pad/tact-switch.html