Extrude surface

I created the dynamo inside the line, then extrude generated surface, “Surface.PointAtParameter” node Why not use?Point flying plane.
extrude into the surface from revit inside the well.
Who can help me solve this problem?
http://dynamobim.org/forums/topic/dynamo-0-7-uv-grid-for-surface/

QQ??20140815232117

Why is it different effects extrusion lines?