Instances Problem
EDIT: SOLVED
Whenever I try to add an instance, the portal file won't open. 
It must have to do with the entity, because I can take a (somewhat longer) detour and copy the instance directly from the file.
P.S search core_babble26 for adventure core
P.S.S in the the sound browser in hammer
P.S.S.S Good luck
FINAL THOUGHT Have you tried saving and reopening the map?
P.S FINAL THOUGHT copying an instances into a map still makes it functional, but very complicated to modify (like elevator transitions)
P.S.S FINAL THOUGHT instances are easier, hopes this helps
Also, make sure the map is saved under "portal2/SDKcontent/maps", or else the instance won't load. I had this problem when I started Portal 2 mapping.
Not in wrath
The REAPER came today
An angle visited this grey path
And took the cube away
spongy, for you 
I'm putting the instance in a saved map, in the right place. It just won't read the .prt file when compiling.
I'm putting the instance in a saved map, in the right place. It just won't read the .prt file when compiling.
When the compiler won't read my .prt file, because of a leak, if you see yellow or red, that means there's a problem
It's not a leak, it happens when I use a func-instance in my map (sorry if misunderstanding)
Try compiling without vvis
Is there a leak in the instance?
PortalStories.com
"Oh, in case you got covered in that repulsion gel, here's some advice the lab boys gave me: DO NOT get covered in the repulsion gel."
This.
Also you have to save the map before any instances show up. I noticed this when I wanted to place an instance when I clicked 'new'.
I would be surpried, they're the offical set.
Try compiling without vvis
Will try.
EDIT: Works, for you! Although, isn't vvis an important part of the compilation?