You have a little nitrate. It will be bright yellow if there is nothing detected. Make sure to shake the nitrate bottles well.
Anyway, this looks like some change. It's less than 15ppm.
Do you really care if you know the exact amount if it's less than 15ppm?
I mean i have the hanna nitrate high range--but no more reagent, can't get any, have other tests too, and i just think any test that can tell it's less 15ppm if just fine.