Cisco AP C9120AXI-Z Registration with WLC 5520 Issue

We have few dozens APs trying to register to WLC , The APs are getting DHCPs, default Gateways, The WLC is located at our DC, connectivity across the network is fine, I can ping the WLC from the LAN network, When I debug capwapp on the WLC i see no attempts from the APs trying to join the network, there other different model APs already registered on the WLC from different sites,we have not installed APs (C9120AXI-Z) in our network before, what am I missing,? gone through Cisco docs, at least i should have see attempted registration by the APs.

- WLC AIR-CT5520-K9 Version :8.10.121.0

- Cisco AP Software, ap1g7-k9w8 Version: 8.10.105.0