I have the Aquarium Pharmaceutical Master Test Kit, and I get readings of 0 for ammonia and nitrites, and fluctuate between 0 and 10 for nitrates. It does read correctly.
Have you read the instructions for the Aquarium Pharmaceutical Test? You have to wait five minutes after adding the drops and shaking the test tube to test. This applies to the ammonia, nitrite, and nitrate test. For the nitrate test you also have to shake solution #2 for a minute before adding its drops, and shake the test tube for a minute before letting it sit for 5 minutes and taking a reading.
HTH