I've got a Black Chocobo and ranked him to Rank S and I've got a Wonderful Chocobo still Rank C, I fed both of them 25 Sylikies Greens and maximized their skills.. Yet when I mate them with a Zeio nut I either get a plain chocobo or a Black Chocobo..

Does the rank effects the chances of getting a Golden Chocobo?

All of my Black Chocobo's parents are Rank S except his grandmother (the Good Chocobo) which is Rank A..

what did I do wrong, what should I do?

sorry for bothering, please help..