Sweep 1 not working


Guess it’s a very basic question but I can not make the sweep work on a very simple definition.
What am I doing wrong?

unnamed.gh (11.0 KB) .


Change the start point of the circle to the top point where the first curve intersect by adjust the seam or rotate the circle; this happened always.

unnamed 2.gh (14.0 KB)

Thank you @anon39580149. Wasn’t aware of this.