Arduino Led On/Off on Ethernet not working

Question

I am trying to On/Off a led from desktop app on C# to Arduino using Ethernet (for serial port communication works), I am connecting to an IP Address to communicate with Arduino, but it looks something wrong with my code or my sketch for Arduino. (I am working with Ethernet shield) my code Arduino

 

//////////INCLUDE HEADER FILES //////////////////
#include <Ethernet.h>
#include <SPI.h>
#include <EEPROM.h>
#include <LiquidCrystal.h>
#include <SD.h>
#include <Wire.h>

EthernetServer server(23 );
String content;
File myFile;
int ledPin = 7;
int  outputpin = 0;
void setup()
{
  IPAddress ip( 192, 168,1,110);
  byte mac[] = {
    0xDE,0xAE,0xBE,0xEF,0xFE,0xED
  };

  Ethernet.begin( mac, ip );
  server.begin();
  if ( ! SD.begin( 4 ) )
  {
    return;
  }

  Serial.begin(9600);
}

void loop()
{
  waitIncommingConnection();
}

void waitIncommingConnection()
{

  String pwd            = "";
  String inData         = "";
  EthernetClient client = server.available();

  if ( client  )
  {
    while ( client.connected() )
    {
      if ( client.available() > 0)
      {
        char recieved = client.read();
        inData += recieved;
        if (recieved == '\n')
        {
          switch( inData[0] )
          {
            case (char)'o' :
              client.println("o");
              digitalWrite(ledPin, HIGH);
            break;

            case (char)'f' :
              client.println("f");
              digitalWrite(ledPin, LOW);

            break;

            case (char)'*' :
              Logout(client);
            break;

            default:
               client.println('d');
            break;
          }
          inData = "";
        }

      }
    }
  }
  else
  {
   client.println('v');
  }
}

void Logout(EthernetClient client )
{
  client.print('x');
  client.stop();

}

 

My C# code

public partial class Form1 : Form
{
    public Client client;
    public delegate void FeedBackCallback(string text);
    public delegate void UpdateMessageBoxCallback(string text);

    public Form1()
    {
        InitializeComponent();
    }

    private void connect_Click(object sender, EventArgs e)
    {
        string ipAddr = ip1.Text + "." + ip2.Text + "." + ip3.Text + "." + ip4.Text;
        string port = portInput.Text;

        if (IsValidIPAddress(ipAddr) == true)
        {
            try
            {
                if (client == null)
                    client = new Client(this);

                client.Connect(ipAddr, port);
                //  client.Send(Encoding.GetEncoding(Constant.EncodingFormat).GetBytes("c"+'\n'));
                disconect.Enabled = true;
                connect.Enabled = false;
                on.Enabled = true;
            }
            catch (SocketException se)
            {
                MessageBox.Show("Unable to Connect.\r\n" + se.ToString());
            }
        }
        else
        {
            MessageBox.Show("Invaild Ip Adrress", "Invaild Ip Adrress", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }

    private bool IsEmptyUserNamePasswordFields(string userName, string password)
    {

        if (userName.Length == 0 || password.Length == 0)
        {
            MessageBox.Show("Password and Username field is required!", "Required Fileds Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            return false;
        }
        else
        {
            return true;
        }
    }

    private bool IsValidIPAddress(string ipaddr)//Validate the input IP address
    {
        try
        {
            IPAddress.Parse(ipaddr);
            return true;
        }
        catch (Exception e)
        {
            return false;
        }
    }

    private void on_Click(object sender, EventArgs e)
    {
        disconect.PerformClick();
        connect.PerformClick();
        try
        {
            if (client == null)
                client = new Client(this);
client.Send(Encoding.GetEncoding(Constant.EncodingFormat).GetBytes("o" + '\n'));
            off.Enabled = true;
            on.Enabled = false;
        }
        catch (SocketException se)
        {
            MessageBox.Show("Unable to Connect.\r\n" + se.ToString());
        }
    }

    private void off_Click(object sender, EventArgs e)
    {
        disconect.PerformClick();
        connect.PerformClick();
        try
        {
            if (client == null)
                client = new Client(this);
client.Send(Encoding.GetEncoding(Constant.EncodingFormat).GetBytes("f" + '\n'));
            on.Enabled = true;
            off.Enabled = false;
        }
        catch (SocketException se)
        {
            MessageBox.Show("Unable to Connect.\r\n" + se.ToString());
        }
    }

    private void disconect_Click(object sender, EventArgs e)
    {
        connect.Enabled = true;
        disconect.Enabled = false;
        client.Disconnect();
    }
}

 

images for the Arduino

 

I don't know where is my problem, the app connect to the arduino, but the On/Off button not works for the led. if u want to see the code foe serial port communication this is the link here, Serial Port