Did China's decision to send low-level officials to a North Korean band concert in Beijing lead to the abrupt event cancellation just hours before the band was scheduled to take stage?That seems to be the case.Citing a Chinese official, a source in China told Seoul-based Yonhap News Agency on Sunday Beijing decided to send vice-ministerial level officials to the event, instead of a higher ranking party leader, following Pyongyang's claim to have developed a hydrogen bomb.North Korea had originally asked that China send President Xi Jinping or Premier Li Keqiang to the concert, but China declined, proposing instead to send one of its 25 highest-ranking officials.Pyongyang agreed.But the source said things took a sudden turn on Thursday when the North Korean leader announced the regime had developed a hydrogen bomb,, also the day North Korea's pop sensation Moranbong band arrived in Beijing.China's state-run news agency Xinhua released a vague statement on Saturday saying communications regarding work-related issues were to blame.But none of that has dispelled speculation about why the Moranbong Band's first concert overseas was called off on short notice.A source familiar with North Korea told Yonhap it's because Pyongyang has declared a period of mourning for its late leader Kim Jong-il, during which singing and dancing are banned.Whatever the reason may be, experts say it seems that North Korea's relations with its longtime ally have been dented, as the performances were aimed at improving Sino-North Korean relations.Connie Kim, Arirang News.