Need some additional information. Can you describe the chalking areas? What does it look like? Is it spread out over the entire wall or focused on small areas? Can this be removed with a damp cloth? What paint sheen was used? How old is your home?
It is possible that the chalking you see isn't the paint but something coming through the paint film from the underlying wall. If this is the case a primer will be needed to seal the wall first then the paint can be added. Any additional information you can provide will be helpful.