I want to attack a target so I mouse over it. There is a handy ghost image of my character suggesting "you can only go this far". Cool. I click to "go that far towards my target" and nothing happens.

From what I understand I have to mouse over a target to be told I'm too far and then make a "best guess" and cursor over somewhere on the ground.

Why can't I just click on an enemy and have that ghost image be the space my character walks to? It's there. The game says this is where I'll end up if I want this way. Great. Why can't I just do it?