[Closed] Help! Lock on Mont Blanc roof box won't budge! 🙁

So I just took my Mont Blanc roof box down from its resting place on the top of the shed, and while I can get the key in the lock, the thing won't even budge. I have oiled the lock and let it sit and then tried it again, but still it won't move. It is as if I am using the wrong key, and yet the key I am using and the lock itself both bear the same numbered stamp.

Any ideas? I know that last year, it was hard to move, but squeezing the lid down allowed it to turn properly. Right now there is nothing in it, so that can't be the problem.

Help! We need to pack for camping! 🙁