Controller LCD contrast issue

I am working on a new Prusa/Graber i3 printer, but am having an issue with the LCD.

Here's what I am using:
Arduino Mega 2560
Ramps 1.4
RepRapDiscount Full Graphics Smart Controller (previous edition w/ potentiometer and red PCB)
Marlin Firmware - Stable branch (downloaded this weekend)

I have been successful in building the Marlin firmware and downloading it to the Arduino. The controller boots up and the startup screen and then info screen display as expected, but I am having an issue with the contrast. The screen is almost entirely white, making it difficult to read. Looking at the display from an angle makes it readable, but obviously, I'd like to resolve the problem.

Changing the setting in the firmware's menu makes no difference. I've also changed the default value in the code and recompiled and downloaded it. The new default value shows up in the config menu, but the contrast is apparently the same.

I have also changed the potentiometer to see if that would effect the contrast, but the pot seems to make no difference at all. In fact, I even removed the pot from the board (desoldered it) and again, the contrast was identical.

Anyone have a suggestion as to what is going on?

I suspect one of the following:
* The Marlin firmware doesn't support the older version of the RepRapDiscount display board.
* The Display board is not functioning as expected
* There is something in the firmware code that I need to change to support the older board.

Any and all suggestions are welcome and appreciated!
-David.