struts2的问题HTTP Status 404 - There is no Action mapped for action name register.

我的jsp<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>

<link href="css/bootstrap.min.css" rel="stylesheet" type="text/css" />
<script type="text/javaScript" src="js/jquery-1.9.1.min.js"> </script>
<script type="text/javaScript" src="js/bootstrap.min.js"></script>


<title>考试管理系统</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>

<div class="container-fluid">
<div class="row-fluid">

<div class="span12">
<h3 class="text-center">
在线考试管理系统
</h3>
<ul class="nav nav-tabs">
<li class="active">
<a href="#">首页</a>
</li>

<li>
<a href="#">登录</a>
</li>
<li>
<a href="#">退出</a>
</li>
<li>
<a href="register/register">注册</a>
</li>
<li class="dropdown pull-right">
<a class="dropdown-toggle" data-toggle="dropdown" href="#">快捷操作</a>
<ul class="dropdown-menu">
<li>
<a href="#">密码找回</a>
</li>


</ul>
</li>
</ul>
</div>
</div>
</div>

<body>
<br>
</body>
</html>
我的 struts.XML
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>

<package name="default" extends="struts-default" namespace="register">
<action name="register" class="com.zyb.action.Register">
<result name="ok">register.jsp</result>
</action>
</package>
</struts>
我的action类
package com.zyb.action;

import com.opensymphony.xwork2.ActionSupport;

public class Register extends ActionSupport {

/**
*
*/
private static final long serialVersionUID = 1L;

public String execute(){
return "ok";
}

}
---------------------------------------action找不到？求解释。谢谢