The babies that died did so over a weeks time. The ones that are alive look great and are growing and getting there feathers. I have a heat light into them and yes they are on medicated chick starter.Why are your babies dying? How old are they and do you have them under warm lights? They need 95 degrees until they start feathering out and you can drop it 5 degrees per week until they get fully feathered. Are they on medicated feed to prevent cocci? One of the reasons chicks die can be due to cocci which is a protozoa parasite. You could try putting them on corid. I put a few ml in a quart of water. I raise mine either on a wire cage so the poop can go through or you can use pine shavings and change them every day.
I have 16 baby ducks that I hatched out of my incubator , they are in another pen but I haven't lost a one. They are all really healthy. I also have some x chicks in another pen and haven't lost one. I have them all in an enclosed building but in separate pens. I told my husband it is because I want these so bad. Ha, Ha. I just hope I don't lose anymore.