You can validate your CYA test by adding some CYA crystals to warm water in a bottle, and shaking vigorously for a while . . . a long while. If you can use really hot water, and let it cool, even better.

Then, after it has sat for a few hours, pour it off into your kit, and test THAT water. If that doesn't turn cloudy . . . then there's a problem with your reagents. If it does, then the problem's most likely with your pool!

Ben