Why did Xiaogang postpone the concert of 15?

Xiao Gang postponed the concert of 15, because he had already made his debut on 15, and the concert was held to put a happy end to his experience on 15. Steve Chou was seriously ill and was silent for many years, which happened to be 15 years since his debut. He held a concert of his own, re-sang his songs that were all over the streets more than ten years ago, and successfully put an end to his 15 life.