Student Not Found means that the city cannot find the student in their database. Go thru the following list to help you find the student.
Does he have a different legal name? Did you enter it by legal Name? Does your school have Male and Female students? If yes is he in a location that correctly identifies him? Try adding his Gender in the Gender column.
You can also try searching for him directly online. If the find hem there just enter his CIR ID in additional info and you can download his immunizations then.