Hello Frank,
Could you explain the issue a bit more? Is there some error that you get when you try to add the device?
Has the device been added to RMS before?
What is the status in Services → Cloud Solutions → RMS? If possible, try pressing the 'Unregister' button on that page.
Also, could you please send me your company ID and the serial number of the device via private message?
Kind Regards,
Andzej