Wireless Connected Client monitoring

I have two wireless controllers that I am monitoring. One Cisco 5508 and one Cisco 9800. I would like my graph to monitor the total number of connected clients. It is currently half working as it is only showing the connected clients to the Cisco 5508 (AP-WLC2) 

I have the WLC-Connected_Clients UnDP assigned tot he 9800 and I see the number of clients connected when I go to the page monitoring that specific device. I have also ensured that i have both controllers selected in the resource that is showing the graph above.

Is there a way to validate that the UnDP is working correctly and gathering the correct information?