[Gmsh] extrusion of a particular surface

[isettagi at libero.it]

Hi,
Thank you in advance for any suggestion you can give me!
I have an irregular surface(plan) and I need to extrude it(because I need 
prisms). But in this surface there are some(a lot) fixed points where the point 
of the mesh have to create a node. 
To do this I use 
Point() In Surface()

The extrusion is ok 
When I mesh it, I have a problems in the surface at the bottom (the new 
created).  It not find the relative point fixed at the top.

I send the file.. maybe is better

It is possible to solve it?
I tried also extrding both point and surface and after pass the bottom points 
in the relative surface, but always errors..

Thank you for the attention and for any help.

Isabella

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