I am a 2nd grade teacher and this is my 2nd year trying to hatch chickens in my room. I have the incubator at 99.5 and the humility around 70. I candled them Monday and it looked like 7 of the 11 would hatch. They were due to hatch Tuesday and there is no movement or "peeping". What am I doing wrong? How long should I leave them in the incubator before I know they aren't really going to hatch. I'm so sad for my students in my class!!!! HELP!!