Turning touchpad off when mouse is connected: Error

Since I play games on laptop it's annoying when I accidentally touch the touchpad accidentally when im using my mouse, so I decided to turn this option off, but when I turn it off, if i disconnect the mouse, the touchpad doesn't work. To some people this might seem as if the touchpad was broken, but no, when I turn this option off it works perfectly with or without the mouse connected. Is there a way I can fix this so the touchpad works with the mouse disconnected and with the option off?