We had a conflict with the limitation of this objectives ability. When a dark side play declares an attack on another objective you can force them to attack this objective instead. From there, where does it go? The card says limit one per turn. Can the dark side player still attack either of the other objectives (including the objective the he declare to attack before) or is he now limited to just the third objective that hasn't been involved up to this point?
The FAQ covers this; I'd recommend checking it out.
The answer is that the original objective can't be engaged again, but Yavin 4 can be.