Not all child pages shown

Hi folks,
I have a problem showing all child pages in the list.

[child_pages cols="1" id="31" skin="simple" list="true" depth="5"]

That means, that the childpage “Turniere” has 3 subpages (Turniere 2016, Turniere 2017, Turniere 2018), but only “Turniere 2106” is listed instead of the childpage “Turniere”.

What am I doing wrong?
I would appreciate any help.

Thanks in advance.

The page I need help with: [log in to see the link]