Okay, so the ap's and the wlc is on the same vlan. Check the time set on the wlc and make sure it is up to date. Reboot the ap and let the ap get an ip address and see what happens. I would console into the ap and capture the log so in case this doesn't work, you can post it and we can go from there.
What model ap, wlc and what firnware are you using on the wlc?