[lily's mom]

I need to revisit and old topic. Lily is awful about getting up in the middle of the night and peeing and then waking me up to go out. In this humidity, the house smells like Lily pee. Tonight I got the black light out which I try to do often. It always about gives me a heart attack to see the carpet. Now for the question. I always treat the places she has peed with simple solution, why can I still see a glowing area with the black light? Does it always show once they have gone to the bathroom on it?