526 Controller has a different OS then the other WLC series like 2100, 4400, 5500.
It is not supported on WCS.
Cisco 2000, 2100, 4100 and 4400, 5500 Series Wireless LAN Controllers; Cisco Catalyst® 6500 Series Wireless Services Module (WiSM), Cisco Catalyst 3750G Integrated Wireless LAN Controller, Cisco Wireless LAN Controller Module (WLCM and WLCM-E) for Integrated Services Routers; Cisco Aironet access points with CleanAir technology, Cisco Aironet lightweight access points, Cisco Aironet lightweight outdoor mesh access points, Cisco 3300 Series Mobility Services Engine (MSE), Cisco Wireless Location Appliance, Cisco Spectrum Expert Wi-Fi, Cisco Context-Aware Software, and Cisco Adaptive wIPS Software.
Monitoring and migration of selected Cisco Aironet standalone (autonomous) access points. Monitoring of the standalone access points of Cisco 800, 1800, 2800, and 3800 Series Integrated Services Routers