Cannot logout with Zend_Auth's clearIdentity()

I authenticate a user with Zend_Auth (LDAP Adapter).

now I have tryed doing a logout script:

public function logoutAction()
{
    $db = Zend_Registry::Get('DbSrv1');

    Zend_Auth::getInstance()->clearIdentity();

    $this->view->title = "Logout";
    return true;
}

When I logout in Firefox, it works. If i do the same in the Internet Explorer 7 and 8, i just to have refresh the page and the user i开发者_JAVA百科s still logged in.

I found an information about the session cache, but it's still not working:

• http://www.chrisshennan.com/2009/04/07/zend-clearidentity-and-ie7-and-chrome-caching-problems/

In addition, I tried to clean the session manually - without success:

unset($_SESSION);
$_SESSION = NULL;

How can I logging out the user?

Thank you! Best Regards

Maybe try redirecting using $this->_redirect('/') instead of rendering/returning? I've never had this issue before.

If that doesn't work, maybe try session_unset and session_destroy php functions.