I heard, long ago, about a mesechta (or entire seder, I can't recall which) of Yerushalmi that was fabricated. It was finally proven to be a fake when a rabbi realized that every mesechta (or seder) in shas has its own unique figure, whether that's a tanna or amora or what-have-you, and this mesechta (or seder) did not.
Is anyone familiar with the specifics of this story, and where can I find more about it?