Portals, to many polygon and Dmoore.

Im little confused about portals and when to use them. I have gotten Smack Dmoore error. Is that saying I have to many polygons. Or is saying I have wrong type brushes. I get Smack Dmoore when making stairs(I even changed it to old style).

Does Portals have to go through the brushes(polygon). Or Glued to them?