Flow along curve small trick

hello there!

I try to flow along a curve a polysurface as I used to do. But this time it does not work properly. It flows in the wrong direction, meaning that instead of having at the end a ‘ring-form’ I have a ‘flat buoy’. I tried to change the parameters, and to flip the vectors direction on the surface, the base curve and the target curve, but it still does not work.

I would like to understand how to control this, without needing to do it 100 times hoping that it will randomly work once.

model1.3dm (522.1 KB)

When I use flow along surface it works. But I dont understand why it does not work with flow along curve…

Sorry for my stupid question, I am still learning rhino.

It seems to work fine here in the latest V6 build: