Can't swing pickaxe

[DancingSkeleton]

I'm playing Penumbra Overture. I am stuck in the Workshop area at the locked "explosives" door. You are supposed to break it down, but the hammer won't break it, and I am having trouble with the pickaxe. I can't get the pickaxe to actually hit anything!! I try to swing it the same way as the hammer, moving the mouse. It moves the pick a little side to side, by I can't get it to actually hit against the door.
1) Is this a bug with the pickaxe, or is there some subtle way to move the mouse that I have not discovered?
2) Is there some other way to get through this door? I need to get the gunpowder inside, to make a fuse to blow up the barrel of TNT so I can get through the cave blockage.