RigidBodies don't respond to gravity?
I've created a simple scene with a RigidBody object, and given it as child nodes a CollisionShape with a BoxShape. I also gave it a MeshInstance with a CubeMesh.
On clicking "Play Scene (F6)", I expected the object to fall, but nothing happens. Are there common "gotchas" I should be looking out for here? Something obvious I'm probably not doing correctly?