Did you clear your cache files? Does it happen in every file or just this one?
Edit: I found a solution. Reinstall Dragon Valley. Don't uninstall it. Just keep reinstalling from your launcher until the egg hatches. The website I read said if you wanted to hit the install button like three times in a row on the launcher before loading up to check. Go for it.
The problem is there was an issue with the installation that causes the game to not recognize the coding for a baby dragon. You can't hatch what isn't there.