If you choose the Bar Magnet option, the loop is held fixed in the plane of the screen. If the loop doesn't rotate, how can any voltage be generated? Try changing the radius of the loop -- what happens? You can also try moving the magnet: left-click on the magnet and drag the cursor up and down. As you move the magnet closer to the loop, the strength of the magnetic field at the loop's position -- and therefore the amount of magnetic flux through the loop -- will change.