Instead of using mouse clicks, you should take a look at the ControlClick() function in the help file of AutoItv3. Dialog box rendering is dependant of the screen resolution and font size. If the font is bigger, sometimes buttons are not at the exact same place. With ControlClick(), you just make sure the right control gets clicked. This way, your script is totally independant from the display resolution. You can also use Send() to send keyboard commands since you almost always can change the focused control with Tab and Shift-Tab. Just avoid using mouseclick when scripting installations... Happy scripting...
