weird, at first, i downloaded the file from 3d tutorial site, i rendered it, and i got a nice output like below.



so, i wanna see what if i added a new cube into it and use a phong (material? or call shader??) like the cynlinder.

but then, i got a total black output?? why? any idea?

btw, you can download the .mb file from here.
https://www.jozvex.com/tutorials/fg2.html
scroll down and here
https://www.jozvex.com/files/fg2/SkylightRoom.zip