Why these boxes don't disappear?

I want to delete boxes in that box. but didn’t.
solid difference also not work.box.gh (12.5 KB)

Help plz

You need to internalize the curve and post the file again or post a Rhino file with that curve.

To just delete the boxes inside the other box you can doi it like this:

box.gh (29.2 KB)

Thank U for notice about rule and grasshopper.
Very Thank U ^-^