user55921: I'm working on this piano project. When I push a button one of the led light is suppose to turn on and a tone comes out of the piezo. The LCD screen is suppose to print out a sentence but I can't get it to work. 
Here is a picture of the board ( everything works except the LCD) I think the problems lies in the power supply but I'm not sure. This is the first time I use a big breadboard.  
Here is my code:
#include <LiquidCrystal.h>

LiquidCrystal lcd(13,12,11,10,9,8);

int p1 = 1; 
int p2 = 2;
int p3 = 3;
int p4 = 4;

int C,D,E,F;  
int buzz = 5;

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

  lcd.print("hello, world!");


  Serial.begin(9600);
  pinMode(p1,INPUT);
  pinMode(p2,INPUT);
  pinMode(p3,INPUT);
  pinMode(p4,INPUT);


}


void loop()
{

  lcd.setCursor(0, 1);

  lcd.print(millis() / 1000);

  C = digitalRead(p1);
  D = digitalRead(p2);
  E = digitalRead(p3);
  F = digitalRead(p4);



  if(C == 1){ 

    tone(buzz,523); 
  }else if(D == 1){
    tone(buzz,587); 
  }else if(E == 1){
    tone(buzz,659); 
  }else if(F == 1){
    tone(buzz,698); 

  }else{
    noTone(buzz); 
  }  
  delay(50); 
}


user55924: The LCD is not powered, there are 2 separated power rails... use a wire to connect both rails.

55921: <p>I'm working on this piano project. When I push a button one of the led light is suppose to turn on and a tone comes out of the piezo. The LCD screen is suppose to print out a sentence but I can't get it to work. </p>

<p>Here is a picture of the board ( everything works except the LCD) I think the problems lies in the power supply but I'm not sure. This is the first time I use a big breadboard. <a href="https://i.stack.imgur.com/ZzXGI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZzXGI.png" alt="Image of the board"></a> </p>

<p>Here is my code:</p>

<pre><code>#include &lt;LiquidCrystal.h&gt;

LiquidCrystal lcd(13,12,11,10,9,8);

int p1 = 1; 
int p2 = 2;
int p3 = 3;
int p4 = 4;

int C,D,E,F;  
int buzz = 5;

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

  lcd.print("hello, world!");


  Serial.begin(9600);
  pinMode(p1,INPUT);
  pinMode(p2,INPUT);
  pinMode(p3,INPUT);
  pinMode(p4,INPUT);


}


void loop()
{

  lcd.setCursor(0, 1);

  lcd.print(millis() / 1000);

  C = digitalRead(p1);
  D = digitalRead(p2);
  E = digitalRead(p3);
  F = digitalRead(p4);



  if(C == 1){ 

    tone(buzz,523); 
  }else if(D == 1){
    tone(buzz,587); 
  }else if(E == 1){
    tone(buzz,659); 
  }else if(F == 1){
    tone(buzz,698); 

  }else{
    noTone(buzz); 
  }  
  delay(50); 
}
</code></pre>
 55924: <p>The LCD is not powered, there are 2 separated power rails... use a wire to connect both rails.</p>
