Cant post new thread

[hinomaru]

I cant post a new thread at my forum, im using vbulletin 4.2.2.

I got this error message :

Not Acceptable

An appropriate representation of the requested resource /forum/newthread.php could not be found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I already read the solution at here : http://www.vbulletin.com/forum/forum...eptable-errors

but still got same error.

But if I post with sort post, the problem not occur.

How to fix this?

Thanks