Contrast problem on i2c?

I want to print something using the A1602 display with I2C shield, but when I print something, everything is white(see attachment).
Here is the code, by the way:

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

LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE); // Set the LCD I2C address, if it's not working try 0x27.

void setup(){
lcd.begin(16,2); // iInit the LCD for 16 chars 2 lines
lcd.backlight(); // Turn on the backligt (try lcd.noBaklight() to turn it off)
lcd.setCursor(0,0); //First line
lcd.print("I2C LCD Tutorial");
lcd.setCursor(0,1); //Second line
lcd.print("Ardumotive.com");
}

void loop(){
}

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Already tried that, it doesn't work. It just changes the brightness.

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Are you using a 1602 with the backpack? The blue potentionmeter on the backpack adjusts the contrast. Have you tried that? Please include pictures and wiring diagram.

Your code says 0X27 and notes say to try 0x27 if not, so you seem to be aware of two addresses, but have you tried 0x3F?

Or maybe you got it working, it's a few weeks old. If you got it working, what was fix?