sawmill skybox

I found it, and put it in the map properties where the skybox should go (or worldspawn entity, w/e) and it won't work for some reason.

Also, I'm trying to use the water from sawmill, but that isn't visible either (probably because of the skybox)

Any hints as to what I'm doing wrong? Also, are there any other settings I should be aware of?

Thanks in advance!

PS: How do I make it rain?