emmanuel and hans,
I think there's another problem, I don't know if this is a bug or something. But today, when I try to render the room that hans edited for me, I discovered another problem/issue. There's still a black part of the windows, when I examined it again, the "Black" part of the window is the ground on the background. The sky on the rendered photo is blue but the ground is black. I tried changing the view from inside the room to outside the room and the rendered photo looks like
this. I don't know if this is an isolated case or if it is happening to other users.
Thank you very much!