The detection color values from the demo may or may not work depending on your lighting. The code worked for us right out of the box, but when we got to regionals, the lighting was so different that the code we had used during the build season was useless. You will have to experiment with different values.
Check this out:
http://joule.ni.com/nidu/cds/view/p/id/1270/lang/en
I haven't taken a close look at it yet, but it looks like a tool that will make color calibration easier.
You may be having problems because of hardware, as others have said, but if you are still having problems after you're sure everything is connected properly, you should just play around with color values. It really does make an incredible difference.