Are you using the API test kit? If so, you want to make sure you are doing the nitrate test correctly. The nitrate test is the only test in the kit that requires good mixing for each step. If you read the instruction, it ask you to shake 5 sec after adding first solution, and then shake the solution 2 bottle for 30 secs before adding it, and then shake for another 1 min and then let it sit 5 min for color to develop.
I am cycling my tank right now as well, for the first 2 weeks I did all the nitrate test wrong and I saw no nitrate at all. Then one day i was bored and read the instruction and realized I was doing it wrong so I did the nitrate test again, and then I am getting 10 PPM nitrate. The ammonia, nitrite, or ph test does not require the rigorous mixing so it's easy to assume nitrate test would be the same.