Unable to check my stairs area

[Anonymous]

Hi,

i have a problem to individuate the stair's walking way of this zone.
I can't see them in the surface calculation or structures page. I used a normal 3D zone and done a solid operation with downward extrusion between the zone and the stair in such a way to let the rise and run be my dispersant surfaces.

What can i do?

Thanks for your support,