Complex sentence: When Capote resold the novella to Esquire, he specified that he was only interested if Attie's photos were used, but to his disappointment, Esquire did not keep this promise.
Split into simpler sentences: When Capote resold the novella to Esquire, he specified that he was only interested if Attie's photos were used. But to Capote's disappointment, Esquire did not keep this promise.