What cause paint to come of ceiling? my bedroom celing has be painted and just latley it started to...

my bedroom celing has be painted and just latley it started to tweet off long the wrapping up ,all flakie and dry what lead to it and what can i do if i want to paint again
Answers:    sand it first to make sure surface is firm later mix pva with hose and paint it onto the ceiling, once dry paint with a dutiful quality emulsion
paint it first next to a pva adhesive solution.