C#, need to receive data from microcontroller

See more:

C#

microcontroller

data

, +

Hello Good Fellows.
Trying to receive data, from mk, using DataReceived and handler event, what i do is -
push a button on a program(code is below) then LED on mk will torn on, then the data should be sent back to program(expecting 1, on byte value, but also tried string value, doesnt work). Sennding side is working, but recieving....not
seems like im missing something. Any help apreciate it. Thx in Further

I checked with mdsn console sample, i receiving data well.
So the problem i think in code above.
There are a sample:
https://msdn.microsoft.com/en-us/library/system.io.ports.serialport.datareceived(v=vs.110).aspx

What I have tried:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO.Ports;

namespace WindowsFormsApplication11
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
         
        
        }
        private void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e) // As i understood, here we configure where i data will be shown,
                                                                                       // trying to get it on TextBox1
        {

            SerialPort sp = (SerialPort)sender;
            richTextBox1.Text += sp.ReadExisting() + "\n";
        }

        private void button1_Click(object sender, EventArgs e)                                      // There are a main actions, first i receive data then send data by a click.    
        {
            serialPort1.Write("\u0001");
            serialPort1.Close();

            System.ComponentModel.IContainer components = new System.ComponentModel.Container();  //  
            serialPort1 = new System.IO.Ports.SerialPort(components);
            serialPort1.PortName = "COM4";
            serialPort1.BaudRate = 9600;
            serialPort1.DtrEnable = true;
            serialPort1.Open();
            serialPort1.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);

          
        }
    }
}