Planes See through?!

[Amnesiaplayer]

Is there a way to ix the "See through the plane" kinda thing, not really THROUGH the plane, but if you make a wall with planes, then on the edge, you ca nsee the outside of your world, in my situation, outside. And that's really ugly because sometimes mini white boxes appear on the edges (white) what I really don't like.

Btw
void SetPropActiveAndFade(string& asName, bool abActive, float afFadeTime);
Activates/deactivates a prop.

How can I Deactivate a prop??
I have this right now:
SetPropActiveAndFade("Alien", false, 0);
I tried almost everything I can, turning false into true etc.
And yes basically, I want the prop to fade out at the start of the level and later if your In "the" are the prop fades in and out. It's a custom entity, but I can't activate/deactivate it from the normal script, So this has to work but how Do I do it
It's SetPropActiveAndFade
So I got in mind: Maybe this works
SetPropDeActiveAndFade
But I don't think that is possible..