The Wrong Man For The Job

Two men, Chaim and Yankel, applied for a job. Both applicants having the same qualifications were asked to take a test by the department manager.
Upon completion of the exam both men only missed one of the questions. The manager went to Yankel and said, "Thank you for your interest, but we've decided to give Chaim the job."
Yankel replied, "Why? We both correctly answered nine questions. I believe I should get this job especially because I have been out of work for much longer than Chaim."
The manager said, "We made our decision not on the correct answers, but on the question you missed."
"How could one incorrect answer be better than the other?" asked Yankel.
"Simple," said the manager. "Chaim put down on question #5, 'I don't know,' and you put down, 'Neither do I.'"