struts 问题：Attribute class invalid for tag link according to TLD

Attribute class invalid for tag link according to TLD
报了上面的那个错误。我的jsp代码如下：
<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib uri="http://jakarta.apache.org/struts/tags-bean"
prefix="bean"%>
<%@ taglib uri="http://jakarta.apache.org/struts/tags-html"
prefix="html"%>
<%@ taglib uri="http://jakarta.apache.org/struts/tags-logic"
prefix="logic"%>
<%@ taglib uri="/WEB-INF/c.tld" prefix="c"%>
<%@ taglib uri="http://struts.apache.org/tags-tiles" prefix="tiles"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html xmlns="http://www.w3.org/1999/xhtml">
<!-- DW6 -->
<head>
<!-- Copyright 2005 Macromedia, Inc. All rights reserved. -->
<title>Home Page</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<link rel="stylesheet" href="css/mm_spa.css" type="text/css" />
<style type="text/css">
<!--
body {
background-color: #330099;
}
.STYLE2 {color: #FFFFFF}
-->
</style> </head>
<body background="img/mm_bg_red.gif">
<img src="img/mm_spacer.gif" alt="" width="50" height="1"
border="0" />
<table border="0" cellspacing="0" cellpadding="0">
<tr bgcolor="#220103">
<td rowspan="2" colspan="2" nowrap="nowrap">
<img src="img/mm_spa_photo1.jpg" alt="Header image" width="215"
height="108" border="0" />
</td>
<td colspan="2" height="55" nowrap="nowrap" id="logo"
valign="bottom">
Quality is the only way to survive and prosper
</td>
<td width="180" rowspan="2">
<img src="img/achievo_logo.gif" alt="header image 2" width="180"
height="84" border="0" />
</td>
<td width="11" rowspan="2">
&nbsp;
</td>
</tr>
<tr bgcolor="#FF9900">
<td colspan="6">
<img src=" img/mm_spacer.gif" alt="" width="1" height="1"
border="0" />
</td>
</tr> <tr bgcolor="#FF080E">
<td colspan="6">
<img src=" img/mm_spacer.gif" alt="" width="1" height="2"
border="0" />
</td>
</tr> <tr bgcolor="#FF9900">
<td colspan="6">
<img src=" img/mm_spacer.gif" alt="" width="1" height="1"
border="0" />
</td>
</tr> <tr bgcolor="#FF080E">
<td colspan="6">
<img src=" img/mm_spacer.gif" alt="" width="1" height="18"
border="0" />
</td>
</tr> <tr bgcolor="#FF9900">
<td colspan="6">
<img src=" img/mm_spacer.gif" alt="" width="1" height="1"
border="0" />
</td>
</tr> <tr bgcolor="#FF080E">
<td colspan="6">
<img src=" img/mm_spacer.gif" alt="" width="1" height="2"
border="0" />
</td>
</tr> <tr bgcolor="#FF9900">
<td colspan="6">
<img src=" img/mm_spacer.gif" alt="" width="1" height="1"
border="0" />
</td>
</tr> <tr>

<td width="165" valign="top" id="navborder">
<br />

<table border="0" cellspacing="0" cellpadding="0" width="160"
id="navigation">
<tr>
<td width="160">
<html:link href="/QASourceShare/home.do?method=abortus"
class="navText">ABOUT US</html:link>
</td>
</tr>
<tr>
<td width="160">
<html:link href="/QASourceShare/home.do?method=process"
class="navText">QA PROCESS </html:link>
</td>
</tr>
<tr>
<td width="160">
<html:link href="/QASourceShare/home.do?method=rules"
class="navText">QA
RULES/POLICIES</html:link>
</td>
</tr>
<tr>
<td width="160">
<html:link href="/QASourceShare/home.do?method=knowlege"
class="navText">DOMAIN
KNOWLEGE</html:link>
</td>
</tr>
<tr>
<td width="160" height="33">
<html:link href="/QASourceShare/home.do?method=skill"
class="navText">SKILL SHARING</html:link>
</td>
</tr>
</table>
</td>
<td width="50">
&nbsp;
</td>
<td width="517" valign="top">
<img src=" img/mm_spacer.gif" alt="" width="305" height="1"
border="0" />
<br />
&nbsp;
<br />
&nbsp;
<br />

<table width="508" height="187" border="0" cellpadding="0"
cellspacing="0">
<tr>
<td height="30" class="bodyText">
<div align="center">
<h1>
<li>
<bean:message key="knowlegeshare.tile.knowlegeshare" />
</li>
</h1>
</div>
</td>
</tr>
<tr>
<td height="24" class="bodyText">
<div align="center">
<bean:message key="knowlegeshare.search.source.type" />
<%--<html:select property="filetype">
<logic:iterate id="TYPE_NAME" name="TypeNameSupply">
<option
value="<bean:write name="TYPE_NAME" property="value"/>">
<bean:write name="TYPE_NAME" property="value" />
</option>
</logic:iterate>
</html:select>
<html:text name="source" property="source"></html:text>--%>
<br>
</div>
</td>
</tr>

<tr>
<td class="bodyText">
<div align="center">
<input type="submit" name="Submit"
value='<bean:message  key="knowlegeshare.button.search"/>' />
</div>
</td>
</tr>
</table>

</td>
<td width="55">
<img src=" img/mm_spacer.gif" alt="" width="50" height="1"
border="0" />
</td>
<td width="180" valign="top">
<br />
</td>
<td width="11">
&nbsp;
</td>
</tr>
<tr>
<td width="165">
&nbsp;
</td>
<td width="50">
&nbsp;
</td>
<td width="517">
&nbsp;
</td>
<td width="55">
&nbsp;
</td>
<td width="180">
&nbsp;
</td>
<td width="11">
&nbsp;
</td>
</tr>
</table>
</body>
</html>
为什么我只要一用<html:``>这样的标签就报上面的那个错，但是我别的页面用没有一点事，？
请问下，这是什么原因？