Bug with curve on surface?

Hello!

I'm new to grasshopper and the blog. I am trying to project a helix-like curve on a cylinder-like surface. I used the curve on surface component but it messes up with the order of points to be linked. It makes a kind of geodesic curve, and goes back on its path...

It looks like the curve can't pass where the cylinder is closed, at V = 0 (the ridge although it is a closed surface). I hope this is understandable...

Since it seems that it should be possible to do such a thing, I was wondering if it might be a bug with the component? Or else do you know a simple way to get around this problem?