It is fine until the Blend command when I want to weld the two edge.
the picture represent my probleme:

in the case1 the probleme is visible
in the case 2 relative fine result.
the different is just the two kind of curve. In the case2 I changed a litle bit the two "edges" for Blend command.
maybe is it an simmilar then previuos Loft-case? the curves directions are changed and the result is ... hmmm... I will check.