Cannot change RD Licensing server mode to 'Per Device'

Hello

Thanks for reading my question.

I have a window server 2012 R2, I have installed the remote desk top service and the RD Licensing Server.

When I change the licensing mode in the "Edit Deployment Properties" dialog -> RD Licensing, I got an error as following on the top of the dialog:

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And I search on the internet, how to change the licensing mode:

1. I have tried to change the group policy:

"Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Licensing"

2. I have tried to change the registry key, and reboot my server:

"HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\RCM\LicensingCore"

After above 2 changes, when I open "RD Licensing Diagnoser", it stills show my licensing mode: Per User.

So, how can I change my licensing mode to "Per Device"? Any idea will be helpful

(By the way, I am a normal user in the domain, I am not a administrator of my domain control, I think Per Device CAL doesn't require me to be an domain control administrator)

Thanks very much