I'm guessing you're using an Arduino Mega2560, you didn't specify that.
LiquidCrystal lcd(52, 51, 44, 45, 46, 47);
Using the SPI pins (51,52) also for the LCD interface is not a good idea. You have so many pins on the Mega, why not using some other pins for the display?
If that doesn't solve your problem, post a wiring diagram of how you connected all the components to your Arduino.