Why was Dev so upset with Sai Baba after his Udyapan ceremony?

Dev was upset because he believed Sai Baba had broken a promise. Dev had lovingly invited Baba to the Udyapan ceremony, and Baba had assured him, "I am coming." As detailed in Chapter 40, Dev waited with great anticipation, expecting Baba to appear, perhaps in some special guise. When the ceremony concluded and he hadn't perceived Baba's presence, he felt deeply disappointed and deceived. He expressed this frustration in a letter to Jog, stating that Baba's words had "turned out otherwise" and that he couldn't understand why the promised experience never came to pass.