Why can my multiple curves collection not be cut/perimeter(BowlBuilder)?

Grasshopper
1

Hi everyone,
I create a collection of curves as you can see in the screenshot, but when I connect it to BowlBuilder plugin Perimeter node, but this Perimeter node didn’t work, why?
I attach my file.
Thank you!

bowlBuilderTemplate_v2.gh (49.0 KB)

ISSUE
ISSUE1333×750 361 KB