Hi Zisheng,
For the Button element, the mouse and joysticks the buttons are normally called ’Button 1’, ‘Button 2’, etc. Note that you need to keep the capital letter and the space when checking the names in code.
You can actually see the correct button names in the drop-down editor for the ‘Monitored Button’ property of the Button element. The editor has the second tab with a list of all buttons on the selected input device (see below).
