Creating surface from 3D element faces

[Shahrzad1989]

Hi all. I am trying to create a mesh-based surface using an Abaqus script. Firstly, I define a geometrical set using the surface. Afterwards, I find the elements belonging to the defined set ("elems") and finally using
p = mdb.models[ModelName].parts[PartName]
p.Surface(face1Elements=elems, name='Surf-1')
I try to create my surface. It is created without errors but it is not a flat surface. Could anyone help please?