How to resolve failed boolean operation. Bodies do intersect with eachother

[Anonymous]

Hi

I have this part (see attachment) that should be made as sum of two bodies (Kanal L and Body57).
"Combine" gives me an error:

Error:   There was a problem combining geometry together.
    If attempting a Join/Cut/Intersect, try to ensure that the bodies have a clear overlap (problems can occur where faces and edges are nearly coincident).
Failed to Boolean bodies together

The Bodies do overlap, Body57 is made as extrusion of a sketch with a projection of Body Kanal L.
Kanal L is made as loft of three sketches in different part.

How to resolve the error? (How to combine the two bodies?)
I`ve spent 2 days on this part working around different errors and I am giving up 😞

[TrippyLighting]

I can combine these parts without a problem.

[HughesTooling · Accepted solution]

Depends on selection order. If you select this body first it fails.

That said I'm suprised it works at all, areas highlighted below tend to cause problems.

Mark

[Anonymous]

Thank You.