huh I have a big problem on post publication on main site

Huh ununderstandable :

look this : http://passion-cheval.net/dossiers-articles/

this is a page wirh "blog and news" template in studio theme. You can see the post is mentioned. But if you clic on the title http://passion-cheval.net/equitation-travail/haute-ecole/la-legerete-cette-notion-oubliee/ it returns a nice 404 Oo

same if i clic on any tag :slight_frown:

What did I miss ?