It looks to me like the pot itself is shading the plant. The leaves are growing near the top because that is where the light is.
If it were my plant I would find a smaller pot (about the size of the root ball you have now) and plant it so the soil surface is just slightly below the lip of the pot. Look at some of the other photos on this site and see how the plants are situated in the containers. Also, there are different types of potting soil and some are significantly better than others. You don't want to use anything with moisture crystals in it as they would keep the soil too moist. Adeniums like to be watered well but prefer excellent drainage at the same time - confusing, I know. Bargain brands of potting mix are rarely a bargain, go for the good stuff and that varies in different areas of the country. Even with quality soil you might want to incorporate something like perlite to increase the drainage. Good luck with your plant.
