The Battlemind power Lodestone Lure states: (emphasis added)
Hit: Constitution modifier damage, and you must pull the target 1 square. Until the end of your next turn, the target can move only to squares that are adjacent to you.
If you cannot pull the target, for example if the target is already adjacent to you, can you use the power? Likewise, can the augment 2 version ("must pull the target 4 squares") be used on a target fewer than 4 squares away?
The rule for forced movement seems to refer to cases where you can use "up to" the amount of forced movement in cases where the wording says, eg, "pull 4" or "pull up to 4." But I can't seem to find a rule about "must pull 4." Is there any ruling that can clarify this issue?