Your set up looks good; I really think it must be the long delivery time. We ordered 125 from Cackle Hatchery last late winter and they delivered in one day. We only lost one which was very weak to begin with...that's a near perfect record. All chicks survived, save for the one, and are doing great. Broody hen is always best but a quick baby delivery is really important. They may have gotten very cold or other scenarios in that length of time. I do highly recommend Cackle Hatchery. So sorry for your loss...hang in there!