The realization relation is commonly explicated via, or identified with, the causal role playing relation. However, the realization relation does not formally match the causal role playing relation. While realization is a relation between a base realizer property and a single higher level realized property, I argue that the causal role playing relation as typically defined is a relation between a base property and two higher-level role properties. Advocates of using causal role playing to explicate realization must therefore decide which (...) of the two kinds of role property they identify with realized properties; I argue that neither choice is good, and the fact that one must make a choice is worse. A search for a new way of defining realization is in order. (shrink)