1st of all, I'm really sorry for the delay, we recently moved the optical part into the Forum and the support is not directly link into it.
Do you have more detail regarding the definition of your model in Speos? Does your display source is located on an exisiting surface, or just behind? what type of Surface optical properties you set on the screen surface? On your result there is some light on the desk that seems to prove that one element is not set as it should. You can also share your project as a .zip file that we can see what could be the rootcause.