Joomla 事件不起作用

这是我的插件代码：

<?php
// no direct access
defined( '_JEXEC' ) or die( 'Restricted access' );
// Import library dependencies
jimport('joomla.plugin.plugin');
class plgContentHideArticles extends JPlugin
{
    /**
     * Constructor
     */
    function plgContentHideArticles( &$subject, $config )
    {
        parent::__construct( $subject, $config );
    }
    /**
     * Example prepare content method
     *
     * Method is called by the view
     *
     * @param   object      The article object.  Note $article->text is also available
     * @param   object      The article params
     * @param   int         The 'page' number
     */
    function onPrepareContent( &$article, &$params, $limitstart )
    {
        global $mainframe;
    }
    function onBeforeDisplayContent( &$article, &$params, $limitstart )
    {
                    global $mainframe;
                    //add your plugin codes here
                    return 'test';
                    //return a string value. Returned value from this event will be displayed in a placeholder. 
                    // Most templates display this placeholder after the article separator. 
    }
}

这是针对 xml 文件的：

<?xml version="1.0" encoding="utf-8"?>
<extension version="3.1" type="plugin" group="content">
  <name>Content - HideArticles</name>
  <author>Saleh Zamzam</author>
  <creationDate>2014-11-23 15:33:47</creationDate>
  <license>MIT License</license>
  <authorEmail>szamdev@gmail.com</authorEmail>
  <authorUrl>www.example.com</authorUrl>
  <version>1.0.0</version>
  <description>Hide Custom Articles from Home page</description>
  <files>
    <filename plugin="hide_articles">hide_articles.php</filename>
  </files>
  <languages>
    <language tag="en-GB">language/en-GB/en-GB.hide_articles.sys.ini</language>
    <language tag="en-GB">language/en-GB/en-GB.hide_articles.ini</language>
  </languages>
  <config>
    <fields name="params">
      <fieldset name="Settings" label="Settings">
        <field name="Ids" type="text" default="" label="Articles Ids" description="" size="100"/>
      </fieldset>
    </fields>
  </config>
</extension>

该事件永远不会被触发。

请注意，插件已成功安装，没有任何错误消息。

我的主要想法是我想从主页隐藏自定义文章，我将根据视图来做到这一点。

$view = JFactory::getApplication()->input->getString('view', '');

知道问题出在哪里吗？