Parsing serial data sent to an arduino

Well i tried the script and it was a bust so i broke it down into smaller and smaller elements until all i had was this

#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

void setup() {
  // set up the LCD's number of rows and columns: 
  lcd.begin(20, 4);
}

void loop() {
  while(Serial.available() > 0)
   {
      
  lcd.setCursor(0, 0);
  lcd.print("LAT:XXXXXXXXXXXXXXXX");
  lcd.setCursor(0, 1);
  lcd.print("LON:XXXXXXXXXXXXXXXX");
  lcd.setCursor(0, 2);
  lcd.print("SPEED:");
  lcd.print(millis()/1000);
  lcd.setCursor(13, 2);
  lcd.print("HDG:");
  lcd.print(millis()/1000);
  lcd.setCursor(0, 3);
  lcd.print("ALT:XXXXXXYYXXXXXXXX");
  // print the number of seconds since reset:
  delay(1000);
  
   }
  
}

no matter what the screen just stays blank. I even tried adding in a delay just in case everything was happening too quickly. Any ideas what i should try now?