Wiper switch ground

[sircrunch]

I'm finishing up my new wiring harness and I plugged in the wiper switch and the wiper motor. I couldn't get anything to work until I took some alligator clips and wires and grounded the body of the switch to the floorboard. So that was the problem all along however I don't understand how they expect you to ground the switch because it is mounted into a plastic bezel. Please advise