Serial Port no Answer

Question

i have a phg ADMITTO100 RFID Reader to read Legic and i try to send some CMD´s to this one but it doesn´t answer.

I follow this example Serial Port

what have I forgotten? Do I have something to install before using a COM-Port?

The CMD is not right because of the LRC byte but shouldn´t the reader say "no, that was wrong"?

Here my code:

        var serialPort = new SerialPort
        {
            PortName = "COM1",
            BaudRate = 9600,
            DataBits = 8,
            Parity = Parity.None,
            StopBits = StopBits.One,
            Handshake = Handshake.None,

            ReadTimeout = 500,
            WriteTimeout = 500,
        };

        serialPort.Open();

        serialPort.DataReceived += new SerialDataReceivedEventHandler((s, e) => 
        {
            var message = ((SerialPort)s).ReadExisting();
            Console.WriteLine(message);
        });

        serialPort.ErrorReceived += new SerialErrorReceivedEventHandler((s, e) =>
        {
            Console.WriteLine(e.EventType);
        });

        var buffer = new byte[] { 0x02, 0x36, 0x00 };
        serialPort.Write(buffer, 0, buffer.Length);