Hello, 
I'm making a wind turbine blade and I have problems with making a rounded tip. I have followed closely a tutorial from Youtube, but it's just not working. Below are pictures of my tip, the desired tip and the error I receive. (Sketch 20 = the airfoil, Sketch 21 is a spline I drew in a plane perpendicular to the plane of the last airfoil section and coincident with the line witch connects the leading edge with the aerodynamic center)

The file is attached.

Can you help me? Kind regards