Can you confirm if the access-point is on the capwap mode ?
In case the access-point is in the mobility express mode you'll need to convert them:
Converting an AP from Mobility Express to CAPWAP Type
To convert a Mobility Express AP into a CAPWAP AP, ap-type capwap from mobility express to lwap
Connect to the Console Port, Telnet or SSH to the AP.
Login to the Mobility Express controller console.
Type: apciscoshell (connect to the AP console)
Login to the AP console using the username Cisco and password Cisco. Both are case-sensitive.
Enter enable.
Type command: ap-type capwap, and confirm .
(Cisco Controller) > apciscoshell
APxxxxxx capwap ap primary-base mywlc_name x.x.x.x
