What theological problem in the Henoticon triggered the excommunication of the Patriarch Acacius, by the Bishop of Rome in the fifth century?

As I read through Oman's treatment of the Dark Ages, I am struck again and again by his references to Catholics (which seems in a contextual sense to mean Christian orthodoxy writ large) and what I read as the seeds of the Great Schism of 1054. Before the Iconoclast dispute, the Henoticon seems to have created an uproar. I am at a loss to understand why, beyond the usual problems of counting how many angels can dance on the head of a pin. As I understand the document, it was *an attempt to heal the rift* between the Monophysites and the rest of Christian orthodoxy at the time. **On what theological basis did the bishop of Rome excommunicate the Patriarch Acacius, for assisting Zeon in drafting the Henoticon ?**