在facebook连接中禁用自动登录

我已经使用这个代码注册网站使用facebook连接

<div id="fb-root"></div>
<script type="text/javascript">
window.fbAsyncInit = function() {

    FB.init({appId: "<?=FB_APP_ID?>", status: true, cookie: true, xfbml: true});
    /* All the events registered */
    FB.Event.subscribe('auth.login', function(response) {
    // do something with response
    alert('Here');
    login();
    });
    FB.Event.subscribe('auth.logout', function(response) {
    // do something with response
    logout();
    });
};
(function() {
    var e = document.createElement('script');
    e.type = 'text/javascript';
    e.src = document.location.protocol +'//connect.facebook.net/en_US/all.js';
    e.async = true;
    document.getElementById('fb-root').appendChild(e);
    }());
function login(){
    document.location.href = "<?=SITEPATH?>users/fb_login";
}
function logout(){
    document.location.href = "<?=SITEPATH?>users/logout";
}
</script>
<fb:login-button perms="user_hometown,email,user_birthday">Login with Facebook</fb:login-button>

当用户第一次登录到网站并且没有facebook会话时，这是正常工作的。如果我已经打开了facebook页面，然后我点击了fb按钮，它不会进入fb_login页面。实际上我想禁用自动登录。提前感谢