Curtain Wall Curved Object

[Anonymous]

(attached photo)
does anyone know why I'm getting this strange segment in the lower frame using this object?

Note: when I Ctrl-Alt click to get these properties to another object whithin this family (such as Curtain Wall Inclined or Curtail Wall Straight) I don't get any problems. (I've downloaded this updated Library from graphisoft's website on May 11, 2005)