I have recently painted over some new plaster...did the usual let it dry out for a week..put on a mist coat...then first coat and in one patch the paint is flaking its about 3 inch wide and 10 inch long ...anyhow sanded down give that patch another coat of a well known matt emulsion,then second coat applied ...looked toady and the same patch is flaking off...it looks as though when you see paint flaking in a damp patch but its all dry...no pva or wallpaper involved..........any ideas what it is and how can i fix it