Dukem

Hey there, so I'm hoping this is the right place to ask this. I've recently generated a random world. What I am trying to do now is to add POIs via the world editor. This seems to be working but when I start a game with that map they don't appear in the game in most cases. What I find pretty strange is that they sometimes do appear but usually I can only see some changes in the ground but I cannot see the building /POI itsself . Can anybody tell me what the problem might be or what do do? Thanks. Dukem