Color matching the MacBook Pro Screen

I am using a MacBook Pro with a Wacom Cintiq 21ux external monitor. I have been trying to match colors on the two displays using Colorvision's Spyder 3 Elite. I have not been able to get the Spyder to recognize that I have two displays. I am trying to figure out whether this due to the MacBook or the Spyder. Does anyone have any experience colormatching the MacBook Pro display with an external monitor? Have you made it work? What calibration device did you use?