It's cuz mblaq can't perform since their manager made a mistake in scheduling them. It was planned before that they would have a concert the day before and after this la concert. Plane flight would make them not meet events on time so they cancelled. With one group gone along with nickhun and jiwoon not performing, they can't get another group with such short notice considering events are scheduled for groups weeks and months beforehand. That's why, because of a scheduling mistake, mblaq can't go, nickhuns scandal, and no replacement, they need to postpone and refund.