Dijital LPG Gösterge Kodu

Merhabalar. Aşağıdaki kodu yüklediğimde şu hatayı alıyorum ; 

C:\Users\PC\Documents\Arduino\sketch_aug11a\sketch_aug11a.ino:7:26: fatal error: LiquidCrystal: No such file or directory

  #include <LiquidCrystal>

                          ^

compilation terminated.

exit status 1
Error compiling for board Arduino/Genuino Uno.

Kod ise : 

 #define lenght 20.0 
 double percent=105.0;
 unsigned char b;
 unsigned int peace;

 #include <LiquidCrystal_I2C_Avrl2C.h>

 LiquidCrystal_I2C_Avrl2C lcd(0x3F,20,4); //

 byte P1[8] = {

  0b10000,
  0b10000,
  0b10000,
  0b10000,
  0b10000,
  0b10000,
  0b10000,
  0b10000,
 };

 byte P2[8] = {

   0b11000,
   0b11000,
   0b11000,
   0b11000,
   0b11000,
   0b11000,
   0b11000,
   0b11000,

 byte P3[8] = {

  0b11100,
  0b11100,
  0b11100,
  0b11100,
  0b11100,
  0b11100,
  0b11100,
  0b11100,

 };

 byte P4[8] = {

  0b11110,
  0b11110,
  0b11110,
  0b11110,
  0b11110,
  0b11110,
  0b11110,
  0b11110,

 };

 byte P5[8] = {

  0b11111,
  0b11111,
  0b11111,
  0b11111,
  0b11111,
  0b11111,
  0b11111,
  0b11111,

 };
void setup() {
 lcd.begin();
 lcd.createChar(0,P1);
 lcd.createChar(1,P2);
 lcd.createChar(2,P3);
 lcd.createChar(3,P4);
 lcd.createChar(4,P5);
  
 }

 void loop() {

int i;
lcd.setCursor(0,2);
unsigned int value = analogRead(0);
percent = value/1023.0*105.0;

lcd.print('Gaz:");

lcd.setCursor(4,2);
lcd.print(value/29.0);
lcd.print(' ');

lcd.setCursor(13,2);
lcd.print(value/3);
lcd.print(' ');

lcd.setCursor(10,2);
lcd.print('Lt');

lcd.setCursor(17,2);
lcd.print('Km.');
delay(1);

lcd.setCursor(0,3);
double a=lenght/100*percent;
if(a>=1) {
for(int i=1;i<a;i++) {
  lcd.write(4);
  b=i;
}
a=a-b;
}
peace=a*5;
switch(peace)
{
  case 4;
  case 3;
  case 2;
  case 1;
  case 0;
  ;}
  for(int i=0;i<(lenght-b);i++){
    lcd.print(">');
  }}
}
}
 }

Arduino ve LCD bağlı,LCD'ye yazı yazabiliyorum. Ancak bu kodda sorun çıkıyor.