Different buttons control different water jet heights. By pressing different combinations of buttons, different fountain patterns can be created. During the rehearsal, Walter sets the water jet controlled by the first button to 1 meter, the second button to 2 meters. During the first actual performance, he presses the second button, followed by the first button. During the second actual performance, he presses the first button, followed by the second button. Unfortunately, the first button is broken during both performances and cannot control the water jet. As a result, although Walter presses the first button, no water is sprayed.