struts2.0中tiles的问题

我在用tiles时，出现错误，每个属性都不识别2009-12-5 14:47:28 org.apache.tiles.jsp.taglib.RenderTagSupport doCatch
严重: Error during rendering
javax.servlet.jsp.JspException: Error executing tag: Attribute 'buttom' not found.
at org.apache.tiles.jsp.taglib.RoleSecurityTagSupport.doEndTag(RoleSecurityTagSupport.java:80)
at org.apache.tiles.jsp.taglib.ContainerTagSupport.doEndTag(ContainerTagSupport.java:80)
at org.apache.jsp.admin.admin_005findex_jsp._jspx_meth_tiles_005finsertAttribute_005f3(admin_005findex_jsp.java:200)
at org.apache.jsp.admin.admin_005findex_jsp._jspService(admin_005findex_jsp.java:91)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:416)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:837)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:640)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1286)
at java.lang.Thread.run(Thread.java:619)
struts.xml配置如下<?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>
    <constant name="struts.enable.DynamicMethodInvocation" value="false" />
    <constant name="struts.devMode" value="false" />
   
<package name="initial" extends="tiles-default">
       <action name="*" class="initial.ExampleSupport">
           <result name="success" type="tiles">admin_index</result>
           <result name="error">/error.jsp</result>
       </action>   
</package>

</struts>WEB-INF下放了tiles.tld和tiles.xml
tiles.xml如下：<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE tiles-definitions PUBLIC
       "-//Apache Software Foundation//DTD Tiles Configuration 2.0//EN"
       "http://jakarta.apache.org/struts/dtds/tiles-config_2_0.dtd">
<tiles-definitions>
    <definition name="admin_index" template="admin_index.jsp">    
       <put name="header" value="/header.html" />
       <put name="menu" value="/menu.jsp" />
       <put name="content" value="/welcome.jsp" />
       <put name="buttom" value="/buttom.jsp" />
    </definition>
</tiles-definitions>
admin_index.jsp代码如下：<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<%@ taglib uri="/WEB-INF/tiles.tld" prefix="tiles" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="sr/admin_index.css" type=text/css rel=stylesheet>
<title>管理员主页面</title>
</head>
<body>
<div id="page">
<div id="header">
<tiles:insertAttribute name="header"></tiles:insertAttribute>
</div>
<div id="body">
<div id="menu">
<tiles:insertAttribute name="menu"></tiles:insertAttribute>
</div>
<div id="content">
<tiles:insertAttribute name="content"></tiles:insertAttribute>
</div>
</div>
<div id="buttom">
<tiles:insertAttribute name="buttom"></tiles:insertAttribute>
</div>
</div>
</body>
</html>