Awww. I'm so sorry to hear that. Are you using egg cartons?
I just had a hatch that were also dead in the shell, pipped through their membrane and died. I think it may have had something to do with the humidity.
Get some mutt eggs, try 4 eggs, allow more fresh air in, through a crack in cover for instance. I have turkey eggs in now and will up the humidity by another dish of water in the center of my incubator.
Give it a break, but don't give up. They say everything happens for a reason, maybe there is a reason that we cannot see, yet will give us experience down the road.
Good luck!