There are two reasons for flats and satin coatings to come out too shinny or Flat coatings to not look flat enough. Thin film coatings in general will look different if sprayed on a cool surface as opposed to spraying on a warmed surface. Thin film coatings will also look different if sprayed light or heavy.
Thin Film Coatings are generally spayed at the sheen you want as an end result. When spraying, it should take about 3-4 passes with your spray gun to get to full color. Check your material flow to be sure you’re not spraying too heavy.