Unable to calibrate monitor

Just bought a new Mac Pro with Snow Leopard installed. Connected my LaCie electron22blueIV monitor to the ATI Radeon HD 4870 graphics card with a mini display to VGA adapter. Went through System Preferences to set all preliminary settings. When I got to Displays>Color>Calibrate, the box where the oval in a square appears, is completely washed out looking. No matter how much I lower the brightness on my monitor, it never appears as it should.

Tried updating to 10.6.2. Did not help.