Arduino GUI immer Off nicht On

International Deutsch
10

so ich habe den Code jetzt mal so geändert das ich jetzt anstatt ON OFF 1 und 0 sende.
Wenn ich jetzt mir dataCOM3 ausgeben lasse bekomme ich für On 11 und für Off 0
Arduino Code

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

String dataCOM3 ;
char d1;
int pin = 13 ;

LiquidCrystal_I2C lcd(0x27, 20, 4);  // set the LCD address to 0x27 for a 16 chars and 2 line display

void setup() 
{
      lcd.init();                      // initialize the lcd
                                      // Print a message to the LCD.
      lcd.backlight();
      lcd.setCursor(3,0);
      lcd.print("Hi hier ist ");
      lcd.setCursor(2,1);
      lcd.print("Jonathan :-)");
      Serial.begin(9600);
      pinMode(pin, OUTPUT);
       pinMode(13, OUTPUT);

}

void loop() 
{
    if(Serial.available())
   {
        lcd.backlight();
        lcd.clear();
        lcd.setCursor(3,0);
        dataCOM3 = Serial.readString();
        d1 = dataCOM3.charAt(0);
         if(d1 == '1')
         {
            lcd.print(dataCOM3);
            digitalWrite(13, HIGH);
            
         }
         else if(d1 == '0');
         {
           lcd.print(dataCOM3);
           digitalWrite(13, LOW); 
         }
   }  
}

Visual Studio Code

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;

namespace Arduino_GUI4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            serialPort1.DtrEnable = false;
            serialPort1.Open();
        }

        private void On_Click(object sender, EventArgs e)
        {
            //Send Comand to the Arduino to turn Pin 13 on 
            serialPort1.Write("1");
        }

        private void Off_Click(object sender, EventArgs e)
        {
            //Send Comand to the Arduino to turn Pin 13 OFF
            serialPort1.Write("0");
        }
    }
}