In Section 21 of his fifth letter to Clarke Leibniz attempts to derive the Identity of Indiscernibles from an application of the Principle of Sufficient Reason to God´s act of creation, namely that God has a reason to create the world he creates. In this paper I argue that this argument fails, not just because the Identity of Indiscernibles is false, but because there is a counterexample to one of the premises that Leibniz cannot satisfactorily rule out.