I cannot hatching from hatching mercenary machine
With a reinforced digi-egg from a certain level, you can hatch with 100%success if you stop to the specified level (3,4 or5). But you must have enough Dragon datas (10x egg's level). Then just "register" your egg at the incubator, and "input" the datas.
You have an average of 40% of success by hatching. You can also buy some level 3,4 or 5 eggs, it won't break before the specified level.
So try several times until you finally hatch an egg.