As per your info you have 220.127.116.11 version on WLC.
interface '13', means you have LAG enabled, it is a logical interface number. As for the AP, it sounds like it is on VLAN 15, and the WLC is hearing the broadcast message on VLAN 15 dynamic interface, instead of getting it on the management interface.
Unless you need clients in VLAN 15, you should remove the interface. If you do need clients there, then put the AP on a different VLAN.
it was always better to have both interfaces on the same subnet, this made it easier and trouble free .