I have caulked all the edges of the room as was cracking I have then used Dulux emulsion on the wall and the paint has cracked really badly on every edge and corner what am I doing wrong this is in every room.

Are you applying second or third coats too soon possibly?

What is the wall made of?
If plaster is cracking, covering it with paint won't solve anything, and caulking only fills in previous cracks.