Are you certain on you incubation days is my first thought? 27 days doesn't sound very promising.
What I look for is movement in the egg. IF the chick in the shell is viable, you would be seeing signs of internal pip and still be seeing signs of slight movement if it was alive.
How does the aircell look? At term, the air cell should be large and dipped at one side. The dip is usually where the chick pips internally.
Could be that the embryo is a late quitter. Possibly. I've had them die at day 18. For some reason they do not get turned properly or an infection has taken them. Sometimes they just die.
At 27 days I would be looking to do a float test on the egg to see if it is viable or not. Not 100% accurate but it will give you an idea where you stand.
Hopefully some of the other BYC members with more hatching experience than I have will pipe in
@Sally Sunshine and BantyChooks...you out there?