When using complex curves (e.g. bezier curves) as a path, Pathcopy sometimes doesn't do what it's supposed to do.
If you see that happening, try the following method;
Get "Weld" Ruby script (also by RickW) from http://www.smustard.com/script/Weld , drop it in "Plugins" folder.
Select the entire path, right-click and "explode" or "explode curves".
Select the entire path again, call up "Weld" from [Plugins] menu.
When prompted "Close curve?" say yes, and no to "Find faces for this curve?".
Now you are ready to run Pathcopy script, but don't erase the unwanted connecting edge created by "Weld" until you finish running Pathcopy successfully.