The thread title is going to get you a slap

Anyway, I don't see the picture, so I have to take a stab in the dark with what you're having trouble with. Make sure you're using the segment doors, and not the entity doors, otherwise they won't cut into the wall. Also make sure the proper script is applied to the door.
EDIT: I think I understand what you're asking now. Try duplicating an existing segment's files, renaming them ("mysegment", etc), and changing their texture paths. Then see if you have any troubles cutting into this segment. That will determine if it's a problem with the segment editor, or something else
Kravenwolf