Shader to match walls

I have made some fake wall pieces. The problem I am having is that although I have borrowed wall textures, they're not shaded right when up against the walls. I've reduced the brightness etc so they're *almost* the same but the walls get slightly darker the nearer the ground they get and I'm not able to replicate that on my object, so it does look kind of different when in place. I did try changing to shader type "wall" but that made them totally transparent!! Any ideas?