I have a Lexus RX-330 that does NOT have the factory towing package. I've installed a receiver hitch. I purchased the trailer pigtail from the Lexus dealer for $63 - ouch. After finding the correct male hook-up for the pigtail, I find there is no power in the receptacle coming from the vehicle's wiring harness. Any ideas on why I just can't plug in the 4 flat pigtail and go?