如果HKLM配置单元中的注册表项没有自定义安全性，则写访问权限要求该代码作为管理员以提升的权限运行。

public void GetReqKey()
        {
            RegistryKey OEMBg = Registry.LocalMachine.OpenSubKey("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Authentication\\LogonUI\\Background",true);
            if(OEMBg != null)
            {
                OEMBg.SetValue("OEMBackground",1,RegistryValueKind.DWord); --<Here the error is reported.
            }
        }

I cannot understand what is wrong with the following script. I have searched thousands of blogs but still cannot find the answer to it.It always throws an exception called "System.UnauthorizedAccessException: 'Cannot write to the registry key.'" .If someone would help me I would be very thankful!.

Absent customization of security for a registry key in the HKLM hive, write access requires that code run with elevated privilege as an Administrator.