From Dev's point of view, why did he believe Sai Baba had broken his promise about attending the Udyapan?

Dev believed Baba had broken his promise because he was expecting a recognizable sign or form, but none appeared in a way he could understand. Chapter 40 shows that after inviting Baba, Dev 'waited with great effort, but no experience came.' Although three uninvited guests—the Sanyasi and his companions—arrived and were fed, Dev did not connect this event to Baba's promise. His mind was veiled by doubt, and he perceived them only as ordinary guests. In his letter to Jog, he lamented, 'I thought You would come under some pretext or in some guise, but why did nothing of the sort happen?' This shows he was looking for a miracle he could comprehend, and when he didn't see one, he felt disappointed and let down.