Stacked surfaces not showing properly

Hello there. I am tryng to construct a filter made of several stacked planar rectangle surfaces. The problem is that they are not displayng properly, but some of them “disappear”. I attach a rhino screenshot, but the problem is in shapediver too, in the uploaded file.
Thank you very much.
This is the model front:


This is how the back should be:

This is how the back becomes visible after I added the front surface, it disappears in the center and only some parts on the corners are visible:

Hi Alessia -

It’s impossible to tell from those images… Perhaps you need to flip the surface normals?
-wim

Thank you Wim, it seemd to me a problem with normals too, but I tried already with Mesh unify normal component.