在下写了个Servlet，用HTML提交，但是运行后出现错误，请各位指教，万分感激：
type: Status report
message: /ServletModule/ServletModule/customerregistration
description: The requested resource (/ServletModule/ServletModule/customerregistration) is not available.
我的XML描述是：
<?xml version= "1.0 " encoding= "UTF-8 "?>
<web-app xmlns= "http://java.sun.com/xml/ns/j2ee " xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance " xsi:schemaLocation= "http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd " version= "2.4 ">
<display-name> ServletModule </display-name>
<servlet>
<servlet-name> customerregistration </servlet-name>
<servlet-class> example_lg_1.CustomerRegistration </servlet-class>
</servlet>
<servlet-mapping>
<servlet-name> customerregistration </servlet-name>
<url-pattern> /customerregistration </url-pattern>
</servlet-mapping>
</web-app>
HTML文件：
<html>
<head>
<meta content= "text/html;charset=gb2312 " />
<title> 用户注册表 </title>
</head>
<body>
<form action= "ServletModule/customerregistration "method= "post ">
<table width= "100% " border= "0 " bgcolor= "center ">
<tr align= "center " valign= "top ">
<td colspan= "2 ">
<h1>
<em>
<strong> 用户注册表 </strong>
</em>
</h1>
</td>
</tr>
<tr>
<td>
<span>
<strong> 用户 ID: </strong>
</span>
</td>
<td>
<input name= "txtuserid " type= "text " id= "txtuserid " size= "45 " maxlength= "35 ">
</td>
</tr>
<tr>
<td>
<span>
<strong> 密码: </strong>
</span>
</td>
<td>
<input name= "txtpassword " type= "password " id= "txtpassword " size= "12 "
maxlength= "10 ">
</td>
</tr>
<tr>
<td>
<span>