Forum:"This housing is suitable" yet no NPCs spawn.

So I'm playing over LAN with my brother. We've beaten several bosses and are approaching hell at this point. We've found several guns, explosives and life crystals, yet we only have the guide and the merchant in our small village. We've waited for several in-game days (10-15, to be more exact), beaten two extra bosses in that time, mined our way down to the lava layer and generally been away from the house. We are completely dumb-founded as of to why no NPC's are moving in, since the game says "This housing is suitable" when using the tool to check it. Any help would be appreciated.

Image can be found at http://cloud.steampowered.com/ugc/576711581919054269/868F5CDE8581E0FF4CEA83CC9F8D4E5B6CA808F8/.