No expert here but your test kit from Wal-mart (I have one too) has a quirk and the Taylor might be similar. Make sure when you are testing for cya that you allow the solution to sit for a while (I let it sit 10 minutes) before putting it in the black dot tube. I lost a lot of stabilizer reagent before I realized the recommended 2 minutes was not adequate. This may not be your problem but I had a similar experience as you before being a little more patient with the test. Hope this helps.