Perhaps the reason you do not see pied's is because the leopard gene works like the platty daddy genetics. Platties can make lessers but lessers together do not make platties. It requires the platty sib to make a platty daddy. The leopard gene may be a dominant gene that allows the pied to come forth, but only when mixed with a pied gene...I believe it is possible in genetics for one gene to be dominant over another but recessive to others. I have always heard that baldness is dominant when mixed with the male "Y" gene but recessive when matched with the "X" in woman. I may be wrong but there it is just the same, something to chew on.