Can't export open splines as Gmask

[edism]

I'm trying to export an open spline(example: a Line) as a GMask, but silhouette won't let me. When I try to export a close Spline(Square or circle) as a Gmask it works great. Is Silhouette made not to export open splines as Gmask?

I'm running Silhouette as standalone on a Mac.