HI Can you please check once again your AAA config and make sure under : "aaa group server radius group_name" You have added radius server that you have created only and there is no typo or something.Thanks.

Please check if you have these two configs in your WLC/Switch :aaa authentication login default local aaa authorization exec default local 

Make sure you have these two configs in your switch : aaa authentication login default local aaa authorization exec default local 

Check your client provisioning policy and make sure it is correct