What basic mistake am I making with this simple loft?

[Steve1]

Hi,
V5

I have two open curves (orange lines) and four portions of my closed profile (pink) satisfying the previous warning open or closed but no both, yet I end up with a mess.
What is best shape for this, should the two U shapes (orange ) be split at tip, or are they ok ?
Should the profile be in 4 pieces or 2 or complete, but complete sees warning.
Lofting failure.3dm (840.0 KB)

Cheers
Steve

[pascal (Pascal Golay)]

Hello - Loft takes curves in one direction only - your setup will work for a networkSrf if you split the red curves at their intersection.

Through the curves suggest maybe a construction more like this:

-Pascal