Programming using QR Code Scanner (GM65/GM66)

Projects Programming
1

Hi guys,
I have a project using Arduino Mega and QR Code Scanner (GM65 / GM66)
I try to make the program like this

#include <LiquidCrystal_I2C.h>
#include <Wire.h>
#include <SoftwareSerial.h>
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE); // set LCD
String readString;
void setup() {
  Serial.begin(9600);
  Serial1.begin(9600);

}

void loop() {
  while (Serial.available()){
    delay(3);
    char c = Serial.read();
    readString += c;
  }
  Serial.println(readString);
  if (readString.length() >0){
    Serial.println(readString);
    if (readString == "ThisShouldbeTheCodefromQRCode")
    {
      lcd.setCursor(0,0);
      lcd.print("Code is OK");
      Serial.println("QRCode is OK");
      readString="";
    }
  }
}

When i try read some QRCode it wont give anything to Serial Monitor
I search the code to this GM65 but i don't found it yet.
Did i bought a wrong Hardware ? or there's a library for this ?
Please, help me . . .
Thanks.