How does Jonas feel when he is skipped at the Ceremony of Assignments? Why do you think he is skipped?

In The Giver, when he is skipped over at the Ceremony of Assignments, Jonas is "stunned." He wonders if he has not heard correctly.
However, when a sudden hush falls over the crowd, Jonas knows that everyone in the community realizes that the Chief Elder has moved from the group of Eighteens to Twenty, leaving a noticeable omission. For a moment, Jonas speculates that the Chief Elder has made a mistake, but he quickly dismisses this idea because the Chief Elder does not make mistakes, especially at the Ceremony of Twelve.
Now dizzy and unable to pay attention, Jonas does not hear the assignment the next boy receives, nor is he very aware of the applause as the boy returns to his place, wearing his new badge. Then, the next number is called, and this continues until the ceremony is near its end.

But she had skipped him. He saw the others in his group glance at him, embarrassed, and then avert their eyes quickly. He saw a worried look on the face of his group leader (Chapter 7).

Jonas tries to shrink from the view of others. He is afraid to turn and see his parents in the crowd while wondering "What had he done wrong?" (Ch.7). Soon, however, the Chief Elder apologizes to the crowd and especially to Jonas for causing him anxiety because she knows that they think she has made a mistake. Then, she calls Jonas to the stage and announces that "Jonas has been selected." These words imply that Jonas has been chosen to be the Receiver-in-training for the community.