If you aren't providing any humidity for the unhatched egg, you will have a problem. The humidity needs to be increased in incubators when the eggs near hatching time, and by putting the egg under a lamp, you dried it out too much. I have no idea how the other egg managed to hatch, but apparently you got lucky. Perhaps some others on this board will be able to help you to correct this situation. Maybe you could LIGHTLY mist the egg, and dampen the shavings below it. Might help some. And---if the egg does pip some, carefully break away the broken spot in the shell, and VERY carefully puncture (pin prick) the membrane below it. This will allow the chick to receive oxygen better. Be VERY careful when doing this. The chick needs oxygen more than food/water at this stage. He has a good supply of energy from the absorption of the yolk at this time. Good luck!