web的一个目录问题

     今天做一个应用时遇到一个目录问题：
   一个应用的目录结构为：webapps/MyNetStore2/Web-INF/
   Web-INF下有一个index.jsp即是以下代码，这个目录下还有一个include目录，内有layout.jsp，sidebar.jsp，header.jsp，     indexContent，footer.jsp,但是像这样写时却找不到include目录下的文件：
     <%@ page contentType="text/html;charset=GB2312"%>
  <%@ taglib uri="/WEB-INF/struts-tiles.tld" prefix="tiles"%>
    <tiles:insert page="/include/layout.jsp" flush="true"><tiles:insert flush="true" page="/include/layout.jsp">
  <tiles:put value="/include/sidebar.jsp" name="sidebar">
  <tiles:put value="/include/header.jsp" name="header">
  <tiles:put value="/include/indexContent.jsp" name="content">
  <tiles:put value="/include/footer.jsp" name="footer">
</tiles:put><tiles:insert page="/include/layout.jsp" flush="true">
    <tiles:put name="sidebar" value="/include/sidebar.jsp">
    <tiles:put name="header" value="/include/header.jsp">
    <tiles:put name="content" value="/include/indexContent.jsp">
    <tiles:put name="footer" value="/include/footer.jsp">
 </tiles:put>

 像这样写时却可以：  
<%@ page contentType="text/html;charset=GB2312"%>
  <%@ taglib uri="/WEB-INF/struts-tiles.tld" prefix="tiles"%>
  <tiles:insert flush="true" page="include/layout.jsp">
  <tiles:put value="include/sidebar.jsp" name="sidebar">
  <tiles:put value="include/header.jsp" name="header">
  <tiles:put value="include/indexContent.jsp" name="content">
  <tiles:put value="include/footer.jsp" name="footer">
</tiles:put><tiles:insert page="include/layout.jsp" flush="true">
    <tiles:put name="sidebar" value="include/sidebar.jsp">
    <tiles:put name="header" value="include/header.jsp">
    <tiles:put name="content" value="include/indexContent.jsp">
    <tiles:put name="footer" value="include/footer.jsp">
 </tiles:put>
如何解释？</tiles:put></tiles:put></tiles:put></tiles:insert></tiles:put></tiles:put></tiles:put></tiles:insert></tiles:put></tiles:put></tiles:put></tiles:insert></tiles:put></tiles:put></tiles:put></tiles:insert>