Mesh boolean operations do not work

Hey guys, I have a very simple challenge:

I want to do some boolean operations with a mesh - in this case a difference, however as a result Rhino as well as GH always only give me the mesh faces adjacent to the subtracting object as a result. Does someone know why this happens? Both meshes are closed…

Cheers, Rudi (5.5 MB)

sorry guys, everything is clear!

The problem was with the mesh. I ran the check command, it revealed that it had several intersecting faces.