Delanuay Edges

Hi!

I chose Delaunay Edges to make my triangle grid on surface and like on the picture its work on one surface but on the second it doesn't work . It's simple code. How can I fixed it?
I read something on this website but I can't figure it out http://www.grasshopper3d.com/forum/topics/delaunay-triangulation-le...

What is the best option to fixed it?