LCD displaying black boxes

Hi!
I’m trying to display some text on my LCD, but when i run my program on the LCD appears only black boxes.
I’m using DEM 16216 SYH-LY Display(here’s the documentation: http://www.tme.eu/pl/Document/75d81a775dc1633337975c25138f1e0b/dem16216syh-ly.pdf) with Arduino Leonardo(i tried also on Yun).

The code:

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() 
{
  lcd.begin(16, 2);
  lcd.print("Hello");

}

void loop() {}

and the second code:

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() 
{
  lcd.begin(16, 2);
  lcd.setCursor(0, 0);
  lcd.print("Hello");

}

void loop() {}

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