请看代码跟错误

tiles.xml

<!DOCTYPE tiles-definitions PUBLIC
        "-//Apache Software Foundation//DTD Tiles Configuration 2.0//EN"
        "http://struts.apache.org/dtds/tiles-config_2_0.dtd">

<tiles-definitions>
<!-- 全局配置 -->
	<definition name="layout" template="WebRoot/layout/layout.jsp">
		<put name="title" value="tiles2简单例子" type="string"/>
		<put name="header" value="WebRoot/layout/header.jsp"/>
		<put name="info" value="WebRoot/layout/info.jsp"></put>
		<put name="body" value="WebRoot/layout/body.jsp"/>
		<put name="footer" value="WebRoot/layout/footer.jsp"/>
		
	</definition>
	<definition name="product.list" extends="layout">
		<put name="title" value="列表显示" type="string"/>
		<put name="body" value="WebRoot/ShowList.jsp"/>
	</definition>
</tiles-definitions>

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" 
	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">
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <context-param>
  	<param-name>org.apache.tiles.impl.BasicTilesContainer.DEFINITIONS_CONFIG</param-name>
  	<param-value>
  		/WEB-INF/tiles.xml
  	</param-value>
  </context-param>
  
  <filter>
  	<filter-name>struts2</filter-name>
  	<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>struts2</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
  <listener>
  	<listener-class>
            org.apache.struts2.tiles.StrutsTilesListener
        </listener-class>
  </listener>
</web-app>

struts.xml

<?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>
	<include file="struts-default.xml"></include>
	<package name="demo" extends="tiles-default">
	<action name="go" class="src.org.zwx.action.DemoAction">
			<result name="success" type="tiles">layout</result>
		</action>
	</package>
</struts>

exception:

严重: Parse Error at line 8 column 55: Element type "put" must be declared.
org.xml.sax.SAXParseException: Element type "put" must be declared.
	at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:236)
	at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:172)
	at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:382)
	at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:316)
	at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.handleStartElement(XMLDTDValidator.java:1960)
	at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.emptyElement(XMLDTDValidator.java:816)

严重: Exception sending context initialized event to listener instance of class org.apache.struts2.tiles.StrutsTilesListener
java.lang.IllegalStateException: Unable to instantiate container.
 at org.apache.tiles.web.startup.TilesListener.contextInitialized(TilesListener.java:60)
 at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3843)
 at org.apache.catalina.core.StandardContext.start(StandardContext.java:4350)
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)

Caused by: org.apache.tiles.definition.DefinitionsFactoryException: XML error reading definitions.
 at org.apache.tiles.definition.digester.DigesterDefinitionsReader.read(DigesterDefinitionsReader.java:270)
 at org.apache.tiles.definition.UrlDefinitionsFactory.readDefinitions(UrlDefinitionsFactory.java:286)

Caused by: org.xml.sax.SAXParseException: Element type "put" must be declared.
 at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:236)
 at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:172)
 at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:382)

 一定是什么地方错了，各位看看，希望有人能解决！