代码点火器会话被破坏

Question

为什么在页面重定向后，codeigniter会话被破坏， 这是我的自动加载配置 $ autoload [＆＃39; libraries＆＃39;] =数组（＆＃39;数据库＆＃39;，＆＃39; form_validation＆＃39;，＆＃39; session＆＃39;）; 我的登录控制器代码是

$result = $this->Loginmodel->verify_user($this->input->post('username'), $this->input->post('password'));//returned as db->result()


        if ($result !== False) {
            //person has an account
                foreach ($result as $obj) {
                $user_id = $obj->user_id;
                $userdesignation = $obj->user_designation;

                $user_access = $obj->user_cpanelpass;

            }


            $sessiondata = array(
                'user_id' => $user_id,
                'username' => $username,
                'loginuser' => TRUE,
                'userdesignaton' => $userdesignation,


            );
            $this->session->set_userdata($sessiondata);


            $sessiondata1 = array(
                'shopname' => 'abc',
                'shopplace' => 'xyz'
            );
            $this->session->set_userdata($sessiondata1);

            $ipaddress = $this->ipaddress();
            $this->Loginmodel->loginloginsert($username, $ipaddress);
            redirect('home');

这在我的系统中正常工作，但在另一个系统中无效。会话在重定向到家庭或任何其他控制器时会自动销毁。