problems inserting anonymous comments

Hi,i'm a new user and I found a problem using drupal 6 on my blog.I'm from italy so my english is not perfect..hope i'll be understandable...

After having installed and configured drupal 6 i see that despite i've selected in permissions to anonymous to see,insert and insert without moderation comments,it happens that their comments aren't visible.I see "1 new comment" below the text, and the comment subject in "last comments" block, on the home page... but i don't see the real comment, even in the administration->comments page.A registered user can instead insert comments without any problem.

in content type i've checked comments options.They are ok,enabled,read writebut below:
anonymous comment:
3 options "anonymous can't ,can or must insert information on the contact".are disabled and i can read: "this option is available only when anonymous users have the permission to insert comments il permesso di inviare commenti in the permissions page".This looks like the permission isn't detected despite the flag is checked.

i've installed modules comment module,of course,and image,firestats modules..

someone can help me?thx in advance.