Ask the Experts / Peep starting point

Okay, whenever I try to click at the edge of the map to make it a peep starting point, a blue box w/arrow inside it won't appear, and whenever I try to go to the next stage of scenerio editor, which is invention setup, a message will appear that says: "Cannot advance to invention setup. You have to select a peep starting point" or something like that. Can anyone help me?

You have to build a path to the edge of the map and the blue box comes automatically. If you have path there try deleting it and rebuilding it.