Through curves mesh error

Hi,

I have problem with through curves mesh.

I have 3 rectangles in 3 levels. I connect their corners with 3 point arcs. I am sure there is no gap in the corners.

when I want to use through curves mesh to make a solid body from these curves I get the error in the following picture:

I also attach the prt file to check.

Can anybody help?

Regards.