[support] Nodes not saved but I don't understand why.

Hi all. I have this problem: some nodes (of one of my contents type) that my user insert from add content are not stored into DB. When the user press to the "Publish" botton I see the POST in httpd-access log, but the user is not redirect to the new node, but to homepage without message of any type.

Most of these errors are from anonymous users.

I have search into DB via phpmyadmin and I see that there is an entry only for "node" table. Where Drupal save the body ?

In node_access I have this :

nid gid realm grant_view grant_update grant_delete 0 0 all 1 0 0

How can I undestrand where is the problem ?

I have tried to "play" with access controll but nothing.

Pls help me.