Get children pages does not work

Hi hope someone can help me with the problem.
This code:

from here http://monstra.org/documentation/theme-template-tags
says that i can get the list of children of the page (Get children pages for a specific parent page)

So i put this code in my template for my page Details, since i have like 7 childrens for details page, but it does not work it show nothing at the place i added that code, and there is no error even on DEV mode

(с) Roman Art
So far So good