Do you have it setup on the controller for "on demand" or "automatic"?

You can specify it per AP from the controller if you like , or the let controller do it for you automagically. If your APs are spread out somewhat uniformly in a given area - automatic may be the way to go. If you have APs strategically positioned and/or are using external antennas such as directional patches, you may want to do some tweaking. Try tweaking the power levels on a few APs and see how the other APs in the area react and how the user environment is affected.