Display Not Working

[ChrisP28]

Hi Guy’s
I have downloaded the Arduino and Marlin firmware for my home build printer.
I have uncommented the line to activate thee discount 4 line display with the built in SD card reader. The file has compiled and uploaded ok but the display was blank. I’ve disconnected the USB connection and connected a 12V supply to the RAMPS 1.4 board. The display flashes but no text. I have connected the board to Prontoface and it connects ok and behaves as expected so I believe the upload is working.
I must have missed something in the set-up of the display, could you advise any drivers to be loaded or extra lines to be changed to set-up the display.
I have a discount full graphics display that I’d like to use but getting the 4 line working is the aim at the moment.
Thanks for taking the time to read this
CP