Don't display text in LCD with ic2

Hello everybody!

I have a problem... I'm trying run this code in my arduino UNO with a LCD with ic2 connection, but the LCD turn on and turn off but does't display text... What's the problem??? My code is this:

#include <LiquidCrystal_I2C.h>

#include <Wire.h>


// Set the LCD address to 0x27 for a 16 chars and 2 line display
//LiquidCrystal_I2C lcd(0x3F,16,2); // Usa el ic2Scanner para saber qué dirección es

#define I2C_ADDR    0x3F  // Define I2C Address where the PCF8574A is
#define BACKLIGHT_PIN     3
#define En_pin  2
#define Rw_pin  1
#define Rs_pin  0
#define D4_pin  4
#define D5_pin  5
#define D6_pin  6
#define D7_pin  7

int n = 1;

LiquidCrystal_I2C  lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

void setup()
{
  // initialize the LCD
  lcd.begin(16,2);

  lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
  lcd.setBacklight(HIGH);
  lcd.home ();                   // go home

  lcd.print("jejejej");  
  lcd.setCursor (0,1);        // go to the 2nd line
  lcd.print("holalala");

  lcd.print("Iteration No: ");
  
}

void loop()
{
  // Backlight on/off every 3 seconds
  lcd.setCursor (14,3);        // go col 14 of line 3
  lcd.print(n++,DEC);
  lcd.setBacklight(LOW);      // Backlight off
  delay(10);
  lcd.setBacklight(HIGH);     // Backlight on
  delay(3000);
}

I'm using LiquidCrystal_V1.2.1 library of Fmalpartida
Help!!!