Diagnosis of Lift B

When I came back I took the “problematic” lift B with more than four other women. The same thing happened, after we “pressed” our designated floors. All the LCD lights of the buttons went off again. The same situation happened. I had it for twice before, after the second time I went home to “think and think”, I guessed that it cannot more than 3 “commands”, residents cannot press for more than three buttons. Just now the “required orders” are: 18, 11, 10, 7. After the four LCD lights went off I took the initiative to press the buttons for floor 7, 10, 11; sounds very helpful right? But actually to “test water” my theory. I am right! So Clever!