Are you using the site? Chocolate ghost comes up for me on the app (I used chocolate het ghost x ghost for the parents). It may be a technical issue, since there's nothing wrong with hypo chocolates to my knowledge. But a chocolate x ghost would only yield het ghosts and chocolate het ghosts, since ghost is recessive. Could you have not held down ctrl and gotten that pairing by mistake?
Likely, it was my first time using the genetic wizard. A friend has a Hypo Chocolate, offered a lot of money for it supposedly and this friend is not a braggart. A large female who has successfully bred in the past.