I recently made a home made incubator too. Can you tell me exactly what you did, maybe that could be the problem. Also, by fine, could you actually tell me what the temp and humidity is? Fine doesn't really tell me what i need to know.
If you could tell me everything about the incubator you made, when the eggs were laid, where they were laid, how long they were laid before they were in the incubator, and anything else you think could be useful we might be able to find out the problem and find a solution.