Run process in remote machine using WMI failed

Question

I am an administrator and want to delegate helpdesk stuff to do some applications silent installs which requires admin. rights, I tried below code and always gets error message 'RPC server is unavailable', I cannot figure out what's wrong with my code, any help will be highly appreciated.

  public static string ahmed(string machine, string username, string password, string domain)
    {
        try
        {
            ConnectionOptions connectionOptions = new ConnectionOptions();
            connectionOptions.Authority = "ntlmdomain:" + domain + @"\" + machine;
            connectionOptions.Username = username;
            connectionOptions.Password = password;
            connectionOptions.Impersonation = ImpersonationLevel.Delegate;
            connectionOptions.Authentication = AuthenticationLevel.PacketPrivacy;

            //define the WMI root name space
            ManagementScope scope = new ManagementScope(@"\\" + machine + "." + domain + @"\root\CIMV2", connectionOptions);

            //define path for the WMI class
            ManagementPath p = new ManagementPath("Win32_Process");

            //define new instance
            ManagementClass processClass = new ManagementClass(scope, p, null);

            // Create an array containing all
            // arguments for the method
            object[] methodArgs =
                {@"mkdir c:\testtest", null, null, 0};

            //Execute the method
            object result =
                processClass.InvokeMethod(
                "Create", methodArgs);

            return "done";
        }
        catch (ManagementException me)
        {
            return me.Message;
        }

        catch (COMException ioe)
        {
            return ioe.Message;
        }
    }