Perpetuum Mobile I

This interesting magnetic perpetual motion machine was first suggested by Johannes Taisnierus and described later in a book by Bishop John Wilkins. An iron ball drops through a hole in the upper straight ramp and rolls down along the lower curved ramp. It goes up through the hole at the bottom and its kinetic energy enables it to roll back up to the top hole, augmented by the attraction to the magnetic sphere on the top of the box. It repeats this path forever. Can you figure out why this perpetual motion machine cannot work?