People tend to confuse between the two push buttons to call the elevator.
An up arrow button has to be pressed when someone needs to go to any of the floors above his and a down arrow has to be pressed if he wants to go below his floor.But people usually misinterpret it and press the up arrow button if they want to call the elevator up to their floor from below.
Even if they might be wanting to go down, they push the up arrow if they are at a floor above.Many times in such a confusion people push both the buttons for they want the lift to stop anyhow at the floor.