How to set hex value to registry using C#?

Question

hear i have a hex value, i don't know what was the original value just this :

[HKEY_LOCAL_MACHINE\SOFTWARE\ESET\ESET Security\CurrentVersion\Plugins\01000400\Profiles\@My profile]
"Username"="test"
"Password"=hex:50,d6,e6,e9,ee,f0,cf,f2,6e,64,03,ad

I want to add these values to registry, I tried using command promp and administrator Privileges with the following command for username :

REG ADD HKEY_LOCAL_MACHINE\SOFTWARE\ESET\ESET Security\CurrentVersion\Plugins\01000400\Profiles\@My profile /v Username /d test /f

it worked like a charm. Then I added the following line to app.manifest File in VS2010 :

<requestedExecutionLevel  level="requireAdministrator" uiAccess="false" />

in order to get administrative privileges and I used the following command witch i found in this site :

private string GETCMD(string com)
    {
        string tempGETCMD = null;
        Process CMDprocess = new Process();
        System.Diagnostics.ProcessStartInfo StartInfo = new System.Diagnostics.ProcessStartInfo();
        StartInfo.FileName = "cmd"; //starts cmd window
        StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
        StartInfo.CreateNoWindow = true;
        StartInfo.RedirectStandardInput = true;
        StartInfo.RedirectStandardOutput = true;
        StartInfo.UseShellExecute = false; //required to redirect
        CMDprocess.StartInfo = StartInfo;
        CMDprocess.Start();
        System.IO.StreamReader SR = CMDprocess.StandardOutput;
        System.IO.StreamWriter SW = CMDprocess.StandardInput;
        SW.WriteLine(com);
        //insert your other commands here
        SW.WriteLine("exit"); //exits command prompt window
        tempGETCMD = SR.ReadToEnd(); //returns results of the command window
        SW.Close();
        SR.Close();
        return tempGETCMD;
    } 

It returns that " The operation completed successfully " but nothing is changed in registry

I tried setting value directly to registry using c# functions but it didn't work.

whats wrong here? how i can set these values to registry ? why it is working by command prompt when I type the command manually but not programmatic, even when the program is started as administrator?

EDITED :

I tried this command :

REG ADD HKEY_LOCAL_MACHINE\SOFTWARE\ESET\ESET Security\CurrentVersion\Plugins\01000400\Profiles\@My profile /v Username /d test /f

AND even this

REG ADD "HKEY_LOCAL_MACHINE\SOFTWARE\ESET\ESET Security\CurrentVersion\Plugins\01000400\Profiles\@My profile" /v Username /d test /f

AND i don't know what to use for password witch is in hex.

EDITED :

I tried using .reg file hear is the content :

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\ESET\ESET Security\CurrentVersion\Plugins\01000400\Profiles\@My profile]
"Username"="test"
"Password"=hex:50,d6,e6,e9,ee,f0,cf,f2,6e,64,03,ad

and i used following code to execute it but it doesn't work even with administrator privileges:

if (!String.IsNullOrEmpty(res))
                {
                    string path = Path.GetTempPath() + "ajdm4SjhCHGS44AhhdJ892.reg";
                    File.WriteAllText(path, res);

                    ProcessStartInfo start = new ProcessStartInfo();
                    start.FileName = "regedit.exe";
                  //  start.Arguments = " -s " + path;
                   start.Arguments = " " + path;
                    Process proc = Process.Start(start);

                    MessageBox.Show("Done!");

                } 

it always shows that operation is completed successfully . but i does not change the registry values.