Question for LCD 4884

Hello all, I am having trouble with my 4884 LCD. http://www.sainsmart.com/sainsmart-graphic-lcd4884-shield-for-arduino-duemilanove-uno-mega2560-mega1280.html The LCD Screen Shield indicates a programmed text, but it countless flickering horizontal stripe across all lines. I mounted it on my Mega 2560. Do you have any idea what seems to be the problem.

Do you have any idea what seems to be the problem.

The fact that we have no idea what sketch you are running. Flickering is usually caused by updating the display too frequently.