If your steering wheel lock funtctions it locks at 180 degrees. Which is hard to get to without power steering/or moving the vehicle. But easy to do if your trying to move a jeep without the key. Try stealing your own jeep and see if you activate it haha.
On another note, as I understand it, the lock is just a pin in the steering column that sets when you turn the wheel. There are other threads describing how it works. Check those out; they might help you identify the problem. I can't imagine the system is too complicated.
Edit it may be more or less degress on a jk but its 180 on my tj.
Also also. I over looked something simple. Were your keys in the ignition when you tried it? If so, it wont lock even if the jeep is still off.