Security

I have a new computer build, that I just joined to the domain. When I go into computer management and attempt to add an Active Directory user to the local power user group, I am receiving the following error. I am logged into the computer with my domain admin account. 

Any suggestions would be appreciated? 

Windows cannot process the object with the name " User name" because of the following error. 

Name translation: Could not find the name or insufficient right to see name.