My First Custom Story - Richard's Manor

[Essen]

I have just question,part with door(You called it in editor "trap"),it's in that room on left when you start,that small room,defeaultly named hatch ceiling door or whatever,it's just door you can have on ground and open it(hope you know what I mean).
How did you made it work?
I tried just test on my custom story and when I opened it,there was wall.
I wanted to look in editor to get info about it,if there is any "door way" for it,is it?