Diana, yes, I think I'll look for another ammonia. But, like you said, even with additives, it should post a reading in the test tube. I'll get something going with fish food.
Midnighttide102, taking a water/ammonia sample to the LFS and have them test with their kit, and the one they sold me, is a good idea.
If for no other reason than to watch them squirm.
Sometimes it seems like nothing is easy.