I´ve been trying around to make a surface from the two curves shown in the attachment. But no chance for me, I can´t get it working...
Both curves are flattened (no paths)
I tried Sweep1, I even shattered curve_01 in two pieces to try with two halfs.
Nothings worked properly.
I simple loft should work fine if you have the bottom curve split in 2. Remember to select the curves in the right order, maybe you need to flip one of the curve's direction.