Why was Dev so upset and disappointed after his Udyapan ceremony?

Dev was upset because he believed Sai Baba had broken a promise to him. He had lovingly invited Baba to his Udyapan ceremony, and Baba assured him he would come. However, on the day of the event, Dev did not see Baba arrive in his familiar form. According to chapter 40, Dev felt he had waited with great effort, but no experience of Baba's presence came to him. He wrote a letter to Jog expressing his disappointment and confusion, feeling that Baba had deceived him and that the promise had turned out to be false, which left him feeling very perplexed.