Hi I have a domain controller that I have installed active directory onto and have set up an account that I want to use for my SQL server installation on another computer that is linked onto the domain. I can search for the account in active directory and I am able to select it into the add new user section in MSSMS, however, when I click add I get 'Windows NT user or group 'DOMAIN\user' not found. Check the name again. (Microsoft SQL Server, Error: 15401) I have googled the Error code and I havent found a solution that has fixed the error. If you have any help I would be greatful Thanks :)