Shadowing, I guess? There should be shadowing on the backdrop, behind the chair.
That's easy enough. Just add a Hue/Saturation layer above the new background layer, and clip it thereto. Then lower the Lightness slider to about -50, and maybe increase the Saturation a bit. That will darken the whole wall, of course, so then you invert the mask.
Then with a 10% white brush, paint on shadowing where you want it.