I am a beginner with chickens and this is my first attempt at incubation. I have a still-air incubator that I kept at 99.5 degrees F and had a humidity of around 60%. I manually turned the eggs three times a day. The last three days of incubation I stopped turning and increased the humidity to 70%. At the same time the incubator had a bad smell in it like it was musty. I had 6 eggs hatch on the 23rd day and when I opened the remaining eggs 5 days later I had 9 eggs with dead, nearly developed chicks. They looked like they had died a few days before the hatch. I discovered I also had two rotten eggs in the incubator. Did I have the temperature too low so they couldn't fully develop or did the rotten eggs suffocate the chicks?