Hardware :: Connecting Macbook To Wacom Cintiq 20WSX?

I have recently purchased a Wacom Cintiq and it works fine with my PC desktop, however, all of my drawing and painting software is on my macbook. I have been having problems getting the Cintiq's display to work.

The Cintiq basically works as an additional monitor, and has a DVI-I cable. The Cintiq came with a DVI-I to VGA adapter, so I simply bought a Mini-DVI to VGA adapter at Best Buy (the apple brand adapter). I hooked the adapters together, turned on the Cintiq then turned on the Macbook and went to "Displays" under "System Preferences". I clicked on "Detect Displays" and the Macbook was able to detect the Cintiq fine. I then did what the Cintiq manual told me to do by configuring the resolutions and all that, but despite this the Cintiq did not pick up any screen from the Macbook. The error message on the Cintiq read that it did not detect any input from my Macbook, which is odd because the Macbook was able to detect the Cintiq just fine.

When I connected my Cintiq to my PC (by use of the DVI-I to VGA adapter as well) the Cintiq picked up the screen within seconds of turning on the PC. What is the problem here? I really do love my Cintiq but it is useless if I cannot use it with my work Mac. Do I have to buy a new adapter or am I doing something wrong with setting up the monitor? Or are the Cintiq and Macbook simply incompatible?