I've got a 1142N access point (AIR-LAP1142N-A-K9) which I'm trying to get t o join a 25 AP 4402 WLC. It starts to download an image, says the image is invalid, and then keeps trying to download an image. The controller itself is running 6.0.199.4. I have another site with the same controller model, t he same software version, and the same AP model that's working fine. The AP was new out of the box and another new AP does the same thing. What could be the cause?