Error in VB component for Principal Curvature lines

hi everyone,

I have a problem with this VB component that I took from this discussion which was made by David Rutten: http://www.grasshopper3d.com/forum/topics/principal-curvature-lines...

I was trying to update the old VB component to my new 0.9.0006 GH release, copying and pasting, but as I'm new in this scripting world I'm unable to solve the error bounced at the line 97 when I link the surface component.

Any suggestion??

thanks in advance!!