Divide Surface not working (SDivide)

Hey guys. Please forgive me if this is a silly question however please do answer me. Thanks in advance.

I am trying to use Divide Surface to get points on a surface. However, it does not work on some of the surface although it is valid surface. Please see attached screen shot and files.
Can anybody help to explain why…
Thank you!!!Divide_Surf…gh (7.8 KB)
Divide_Surf.3dm (106.5 KB)