So the mouse is covering an area on your Main characters window? Yet you want your Clones to cast a spell in that area using Mouseover?

Yeah, it doesn't work like that.
The mouseover command works when the Mouse is over something in the Window that its being called from. I.E The mouse has to be active in the clones window, not in your mains window.

Sorry, but doing it the way you are attempting just won't work.