You won't make an albino ivory from breeding your albino yellowbelly to an albino. You need to have yb and albino on both sides to do that. The Albino YB paired with an Albino gets 50% Albino and 50% Albino YB. If you were to get a Yb het for albino then you have a chance of Albino Ivory.
Percent Fraction Morph
12.5% 1/8 Het. Albino
12.5% 1/8 Albino
25% 2/8 Yellow Belly Het. Albino
12.5% 1/8 Albino Yellow Belly
12.5% 1/8 Albino Yellow Belly
12.5% 1/8 Ivory Het. Albino
12.5% 1/8 Albino Ivory