what brand of your drop checker? Did you use kH = 4 instead of your tank water to dilute the test solution?
Aquascaping is a marriage between Art and Farming
My Blog: http://aquatic-art.blogspot.com/
drop checker reaction is not immediate. i would say 40minutes to 1.5 hours.
If you want to verify. take it out of the tank for a while, you should see it change to blue or darker green after 5-10 minutes.
Learning the hardway, not the highway.
Photo Blog - Aquarium.allowed.org
"if he cant be bothered to take the time to write his question properly, why should I take the time to answer him."