Not sure if Ford has keys like Chevy does but Chevy has smart keys now. There's a little plus (+) sign stamped in the key that means there's a chip in the head of the key, and that chip coincides with the computer of the truck saying everything is ok. If you have a key cut that doesn't have that chip in it supposedly it's not supposed to start the engine. Maybe yours is something like that, or it gives the engine a limited range? I don't know why things have to be so complicated. It's supposed to eliminate risk of theft, but of course it implies that whoever is attempting to steal has access to your key to cut a copy. I don't know about you but my key stays in my pocket 95% of the time.