Codeigniter Form Validation总是返回false

我在这个上花了太多时间，我觉得我已经对代码视而不见了。表单验证在运行时总是返回FALSE，我无法找出原因。

new_map（）函数首先显示表单，在提交表单时（当然在map_name字段中设置了值），表单验证运行返回false，表单重置后不会显示任何错误。我错过了什么？？

控制器：

public function new_map()
{
    $data['extra_assets']['js'][] = 'app/admin/maps.js';
    $data['title'] = 'Add Map';
    $this->form_validation->set_rules('map_name', 'Map name', 'required');
    if ($this->form_validation->run() == FALSE)
    {  
        $this->load_admin_view('admin/ae_map', $data);
    }
    else
    {
        $this->load->model('maps_model');
        echo 'inside true';exit;
        // Upload map
        if ($this->maps_model->upload_map())
        {
            redirect(site_url('admin/maps'));
        }
    }
}

型号：

public function upload_map()
{
    $config['upload_path'] = root_path() . 'space/maps/';
    $config['allowed_types'] = 'gif|jpg|png';
    $this->load->library('upload', $config);
    $map_name = $this->input->post('map_name');
    if ( ! $this->upload->do_upload('map_file'))
    {
        $error = array('error' => $this->upload->display_errors());
        echo $this->upload->display_errors();exit;
        return FALSE;
    }
    else
    {
        $data = array('upload_data' => $this->upload->data());
        // Insert map into database
        $options = array(
                    'm_file' => $data['upload_data']['file_name'],
                    'm_name' => $map_name
                 );
        $this->insert_map($options);
        // Create a thumbnail of this map
        $this->generate_map_thumb($data['upload_data']['file_name']);
    }
    return TRUE;
}

视图：

<div class="modalContent" style="width: 300px; height: 250px;">
<h1><?php echo $title; ?></h1>
<?php echo validation_errors(); ?>
<div id="MAP_FORM" class="formListing">
    <?php echo form_open_multipart('admin/new_map'); ?>
    <ul>
        <li>        
            <div><label>File: </label></div>
            <div><span><input type="file" id="MAP_FILE" name="map_file" /></span></div>
        </li>
        <li>      
            <div><label>Name: </label></div>
            <div><span><input type="text" id="MAP_NAME" name="map_name" value="" /></span></div>
        </li>
    </ul>
    <br />
    <input type="submit" value="Submit" id="SUBMIT_MAP" name="submit_map" />
    <?php echo form_close(); ?>
</div>