Lots of things effect hatch rates. If your temps or humidity was off, even a bit, eggs won't hatch. If your eggs weren't stored correctly before setting or they were set wrong, they won't hatch. If they were from poor stock, infertile, or from stock that was not healthy, they won't hatch. If you didn't lock down properly, they won't hatch. Even the place you incubate them can effect hatch rates. Shipped eggs can have low hatch rates.
So it is hard to say why they didn't hatch.
What temp and humidity setting did you use? Was this a forced or still air incubator?
Where did you get these eggs? How were they stored before setting?
Temp and humidity at lock down and did you open all your vents?
Anything else you can tell us about your situation?