facebook登录问题与codiegniter

Question

登录Facebook后出现此错误信息，如何修复？

这是我的索引功能

    if($this->facebook->is_authenticated())

    {
    $data['user'] = array();
        $user = $this->facebook->request('get', '/me?fields=id,name,email');
        if (!isset($user['error']))
        {
            $data['user'] = $user;
        }
        $this->load->view('home',$data);


    }
    else{
    $data['user'] = $this->facebook->request('get', '/me?fields=id,name,email');
    $this->load->view('signin',$data);
}

数组（[错误] =＆gt; 0 [消息] =＆gt;您必须提供访问令牌。）