Why did Dev believe that Sai Baba had deceived him regarding the Udyapan ceremony?

Dev felt deceived because he had personally invited Sai Baba to his Udyapan ceremony, and Baba had assured him, 'I am coming.' However, Dev failed to recognize Baba's arrival. As detailed in Chapter 40, Baba came in the guise of a Sanyasi with two companions, but Dev's mind was veiled by 'Maya,' and he only saw them as ordinary uninvited guests. After the event, Dev remained doubtful and disappointed, believing no miraculous experience had occurred. He wrote a letter to Jog complaining that Baba's words had turned out to be false and that he had been let down, not understanding that the promise had indeed been fulfilled right before his eyes.