Broken book.module hierarchy

Sitemap doesn't display correctly a deep hierarchy of book modules.
See an example: http://drupalcookbook.ru/sitemap

And how it should be: http://drupalcookbook.ru/ (here works my snippet).
This is a google translation of snippet: http://66.102.9.104/translate_c?hl=ru&sl=ru&tl=en&u=http://drupalcookboo...