I'm assuming you are running Microsoft NPS as your RADIUS server, you should check the event viewer on the server running NPS. You can find the NPS logs under custom reports, security, and NPS. This will tell you two things... 1. Is NPS hearing communication from the AP? if not, you need to make sure the AP is a RADIUS Client in NPS. 2. you'll get a reason code from the NPS log that will point us to the problem. I'm also assuming your AH config is correct because it's working on some AP's.
