roof and roof wizard

[Anonymous]

Hello.
I built this roof using two single-plane roofs and then subtracted them with two slabs, which are hidden in the image. I would like to add the roof's wooden structure using the roof wizard, but when I do it, it does not recognize any subtraction or intersection, as can be seen in the right part of the image and the structures of the two roofs do not match.
Does anybody have an idea of how I could solve this?
Thank you.

[Anonymous]

Thank you very much. I followed all steps and it went well.
Thank you.