PlayerStart area refuses to work

[Thesus]

I've tried moving the spawn area everywhere, on the bottom of the floor, in the middle, yet every time I try playing the map, it puts me out in the void and I just fall to my death. The wiki doesn't really help as there are no tutorials explaining how to place a playerstart correctly. I have a feeling it might be because I don't have a script file for it or something, but I kinda doubt it.

Screenshot:
http://filesmelt.com/dl/mapproblem.png