are you on a hill parked by any chance? if so the wheel is very tight, it has to move a little bit, they all do, push a bit harder each way till you feel it move. then push in the key and turn it you may even have to wiggle the key back and fourth.
when on a hill parked, the weight of the car is pulling on the wheels, if the wheels are turned some, it can really pull hard on the steering wheel, and holds it super tight to the wheel lock. pushing it what ever way it moves takes the wheel off the lock and lets it unlock.
