ctrl + z

Hello, I have macromedia flash 8 and I recently got a drawing tablet. The tablet is called "XP Pen Deco 01 V2". There's a button on the tablet that I can press to undo, but when I press that button on macromedia flash 8, I sometimes have to repeadetly click on the button so that it could actually undo. Do you know why this is happening? Maybe my tablet is too new for Flash? I use a windows 10.