Firstly you need to understand , a controller works at faster speed compared to lcd so before initializing LCD you need to keep a delay of min 20ms in controller programming.
Secondly check foll voltages at controller pins :
Vcc – 5V
ALE – 1.68V
PIN 18 and 19 – (around) 2.18 to 2.8 V
and then tell me if the problem remains !!!