Solid difference not working

Hi everyone!
I am a beginner in Grasshopper
I want to make a circle hole but solid difference is not working well
Could anyone help me?
project.3dm (89.2 KB) project.gh (16.2 KB)

The surfaces you want to cut holes into are not a solids. Try this instead:


brep_holes_2020Dec8a.gh (16.6 KB)

thanks a lot!!!1