Has anyone got any ideas for how to get paint to stick to the outside of my house!?

The house was rendered until about 4 years ago, but I stripped it all off as it was blowing all over the place. Decided not to re-render but paint but now 3rd coat of Johnstones pliolite smooth masonry paint is peeling off all over the place. Some of the bricks have spalled and shedding the paint, but in many places it's just peeling off individual bricks with good faces. Any idea folks? Thanks.