Well here's the issue Rail is talking about:
The Prince of the Bird Tribe (Marteva) approached Kouichi with the task of hatching an egg the Prince claims is that of his younger brother. He told Kouichi that they tried everything to get it to hatch but to no avail. This is why Rail intervened. He found that the Prince lied about the Bird Tribe trying everything to get the egg to hatch. Rail suspects that it's not possible for the egg to be the next crowned Prince because no one of the Bird Tribe knew of the egg and no research material was recorded as borrowed from the Sage Tree (great elven library where this knowledge is kept) from any royal staff of the Bird Tribe. Rail said that due to the Bird Tribe's practice in making the youngest son the next king (due to their short life span), that it should be natural for not only all peoples of the tribe to hear of the news but that if an issue arises that any and all methods must be researched to resolve the issue. But that didn't happen, therefore Rail suspects that this egg is something else.
So basically they weren’t treating the egg right because they don’t want it to hatch? I’m confuse. Why else wouldn’t they speak of a new egg? Why doesn’t the egg want to hatch? Did it realize it was unwanted so it chose not to and because the bird royals don’t care, they just ignored it until they pin the blame on Koichi? Someone with a bigger brain and comprehension skill explain to me.