Why?

News published on 23.03.09: "Amid mounting pressure from the government, vice-chancellor(VC) of Bangabandhu Sheikh Mujib Medical university(BSMMU) and its three senior officials resigned yesterday".
News published on 25.03.09 in the same paper: " The government yesterday appointed a new vice-chancellor (VC) two pro- VCs and treasurer of Bangabandhu Sheikh Mujib Medical University (BSMMU).” There is nothing wrong with it.
But we may recall that the immediate past VC was appointed during the last caretaker govt. when he faced tremendous opposition from the four party alliance followers, but still he could take office and continue working. He was in a more or less similar situation after the new government took over. Why?