Well you also have to factor in the Black eyed leucy gene.
Platty x platty would give you ivorys and plattys, ivory x platty would give you ivorys, ultra ivorys and plattys and then ivory x ivory is how you make the black eyed. It is a strange gene, as it is almost like a hidden ressive when you get the ivorys. When you hit the "ressive" youll get the BEL and if not, then you get the super form of the codom.
That's just my take though.