I had the same problem when I started. It may be that your mouse is not working properly. I was using a G5 and it would not accept the wheel mouse click to execute the order. I went into game setting and re-mapped the action that is assigned to the mouse wheel to one of my keys that are close by and it works fine now. Try giving that a try. I am still trying to adjust my G5 to accept the buttons but not even the back button will work. If anyone else is having this problem and knows how to fix it please let us know.