Kangaroo, Constraint Surface?

Hey everyone!

Just installed Kangaroo but I'm having some problems getting the ConstraintSurface function to work!

I have a bunch of geometries and I just want to map it onto a surface.

Daniel Piker posted a video of this here: http://www.grasshopper3d.com/forum/topics/packing-circles-on-curved...

And here's my attempt at it.

Nothing's feeding out of it at the moment.

Would be really grateful if someone could help or offer some advice!

Cheers,

Ra