Makes more sense now. Yes, by using Prime you are getting a false reading, as Prime doesn't eliminate ammonia, rather it binds the ammonia to ammonium. With a fishless cycle, you shoudnt be using Prime, as you are altering the food source for your bacteria. Skip the Prime, add enough ammonia to get to 2ppm. If your filter converts that to nitrate in a decent amount of time, you are ready for fish. Don't wait too long, next day perhaps to get fish, as the fish will be your new ammonia source. You want to preserve and grow the bacteria colony you already have.