关于The end tag "</html:html" is unbalanced的问题

请高手们帮看一下，这个为什么老是报错，感激不尽
<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<%@ taglib uri="/struts-tiles.tld" prefix="tiles" %>
<%@ page contentType="text/html; charset=GBK" %>
<html:html xhtml="true" lang="true"><head>
<title>digitalstore</title>
</head>
<body>
  <div align = center>
    <table cellspacing="1" cellpadding="0" width="770" border="0">
      <tbody>
        <tr>          <tiles:insert attribute="header"/>        </tr>
        <tr>
          <td valign="top" width="25%" height="350">
          <tiles:insert attribute="menu"/>
          </td>
          <td valign="top" width="75%" height="350">
          <tiles:insert attribute="content">
          </td>
        </tr>
      </tbody>
    </table>    <tiles:insert attribute="footer"/>
  </div>
 </body>
 </html:html>报错内容是这样的"layout.jsp": org.apache.jasper.JasperException: file:D:/DigitalStore/WebModule1/layout.jsp(32,1) The end tag "&lt;/html:html" is unbalanced