CakePHP错误:请求地址'/unsigned_images/index'在此服务器上找不到

我是一个初级CakePHP开发人员。我遇到了一个错误:请求的地址'/unsigned_images/index'在这个服务器上找不到。

我使用以下代码:

模型:应用程序/模型/unsigned_image.php

<?php
class UnsignedImage extends AppModel{
    var $name = 'UnsignedImage';
    var $useDbConfig = 'tabletApp';
    var $useTable = 'unsigned_images';
    //var $useTable = false;
}
?>

控制器:app/controllers/unsigned_images_controller.php

<?php
class UnsignedImagesController extends AppController{
    var $name = 'UnsignedImages';
    var $pageTitle = 'Hello world!';
    var $helpers = array('Javascript');
    var $components = array('Auth', 'Slogic');
    function index(){
        $this->layout = 'default';
        $this->set('data','Hello World!');
        $this->set('unsigned_images', $this->UnsignedImage->find('all') );
    }
}
?>

视图:app/views/unsigned_images/index.ctp

<div style='font-weight: bold; margin: 0 0 10px 0;'>View All Signatures</div>
<table>
    <tr>
        <th>ID</th>
        <th>Session ID</th>
    </tr>
    <?php 
        foreach( $unsigned_images as $unsigned_image ){
            echo "<tr>";
                echo "<td>{$unsigned_image['UnsignedImage']['id']}</td>";
                echo "<td>{$unsigned_image['UnsignedImage']['session_id']}</td>";
            echo "</tr>";
        }
    ?>
</table>

• 我有unsigned_images表在我的数据库
• 当我访问http://somedomain.com/unsigned_images/index/时，它打印错误。
• 当我只是使用var $useTable = false;在模型中，没有打印错误。

非常感谢您的帮助!:)