CodeIgniter 3 Flashdata 始终显示问题的解决方案

<?php if($this->session->flashdata('msg')){ ?>
   <div class="alert alert-danger"><?php echo $this->session->flashdata('msg');?></div>
<?php } ?>

<form action="<?php echo base_url('Login/authentication'); ?>" method="post">
  <input type="text" name="employeeNum" placeholder="Employee Number">
  <input type="password" name="password" placeholder="Password">
  <button type="submit">Login</button>

  <?php if($this->session->flashdata('msg')){ ?>
    <div class="alert alert-danger"><?php echo $this->session->flashdata('msg');?></div>
  <?php } ?>
</form>

public function authentication(){

    //post user input
    $empNum=$this->input->post('employeeNum');
    $pwd=$this->input->post('password');

    $user=$this->empNumAuth($empNum, $pwd);

    if($user) {

        if($user['PrivilegeLevel']==='1'){

            $this->session->set_userdata($user);
            redirect('AdminDashboard/view');

        }
        else if($user['PrivilegeLevel']=='2') { 

            $this->session->set_userdata($user);
            redirect('UserDashboard/view');
        }

    }

    else {
        $this->session->set_flashdata('msg','الرقم الوظيفي او رمز الدخول خاطئ');
        redirect('Login/LoginPage');
    }
}