I had some that had thicker shells than others, but that did not seem to make a difference when hatching. Does your house fluctuate temperatures? or is the incubator near a window, or heater vent? the external temp stays between 64 and 68 where my incubator is so the internal temp is less likely to fluctuate. I got http://incubatorwarehouse.com/incubator-remote-thermometer-hygrometer.html
and it works wonderfully. You might also make sure there is light coming in through the windows on the incubator. All of my eggs hatched during daylight hours when there was ample light, I do not know if there is a correlation or not, but its worth a try. I wish I could offer you more, good luck and keep up the faith. They will pop out soon enough.
one hatched at 12 pm today very quickly! Yes there is a lot of temp flucuations. I didnt want to put it in my closet because there are no vents in there and cold. Maybe should have tried anyway.