救命：一个非常棘手的问题，也许对各位来说是一个非常简单的问题

关于weblogic运行servlet的问题：
在D:\bea\wlserver6.1\config\mydomain\applications\DefaultWebApp\WEB-INF\classes目录下有两个servlet文件如下： HelloWorld.class和RequestHeaderExample.class

HelloWorld.class的源代码是：

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class HelloWorld extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException {
PrintWriter out=response.getWriter();
out.println("Hello World");
}
}



RequestHeaderExample.class的源代码是：

import java.util.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class RequestHeaderExample extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws IOException, ServletException
{
res.setContentType("text/html");
PrintWriter out = res.getWriter();
Enumeration e = req.getHeaderNames();
while (e.hasMoreElements()) {
String name = (String)e.nextElement();
String value = req.getHeader(name);
out.println(name + " = " + value);
}
}
}


web.xml文件是这样的：
<?xml version="1.0" ?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 1.2//EN" "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">
<web-app>
<servlet>
<servlet-name>HelloWorld</servlet-name>
<servlet-class>HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorld</servlet-name>
<url-pattern>/HelloWorld/*</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>RequestHeaderExample</servlet-name>
<servlet-class>RequestHeaderExample</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>RequestHeaderExample</servlet-name>
<url-pattern>/RequestHeaderExample/*</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>


为什么在地址栏里面输入http://61.167.21.118:7001/HelloWorld就可以运行
而输入http://61.167.21.118:7001/RequestHeaderExample就显示404错误呢？？