我照JSF写的入门程序，但是报错说找不着Face Servlet实例。

我现在的问题就是网页能找到index.jsp文件。如果我把<f:view></f:view>删了的话，能显示一个带标题的网页。但是，报错
说无法初始化FaceSevrlet。我想是不是，我的   |-myface-api-1.1.4.jar
  |-myfaces-impl-1.1.4.jar文件放错了，但是我放在WEB-INF的lib中也出现这个错，我再查web.xml,觉得FaceServlet没有写错啊
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>
            javax.faces.webapp.FacesServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
不就是在WEB启动时初始化一个Faces Servlet的实例吗，
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.faces</url-pattern>
    </servlet-mapping>
   
    <welcome-file-list>
        <welcome-file>pages/index.jsp</welcome-file>
    </welcome-file-list>
所有的*.faces资源对应的*.jsp文件。那错误在哪里呢，真的想不出来。
严重: Faces context not found. getResponseWriter will fail. Check if the FacesServlet has been initialized at all in your web.xml.
2007-6-5 8:22:29 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at javax.faces.webapp.UIComponentTag.setupResponseWriter(UIComponentTag.java:929)
at javax.faces.webapp.UIComponentTag.doStartTag(UIComponentTag.java:310)
at org.apache.myfaces.taglib.core.ViewTag.doStartTag(ViewTag.java:70)
at org.apache.jsp.pages.index_jsp._jspx_meth_f_view_0(index_jsp.java:86)
at org.apache.jsp.pages.index_jsp._jspService(index_jsp.java:61)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Unknown Source)hello
  |- src
  |- JRE System Library
  |- J2EE 1.4 Library Container
  |-myface-api-1.1.4.jar
  |-myfaces-impl-1.1.4.jar
  |-META-INF
  |-pages
     |--index.jsp
     |--welcome.jsp
  |-WEB-INF
|--lib
    |--faces-config.xml
    |--web.xml
  |-work
这是web目录结构。
以下是代码：
web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
 
 <web-app 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"
    version="2.4">
 
    <description>
        JSF Demo
    </description>
    <display-name>JSF Demo</display-name>
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>
            javax.faces.webapp.FacesServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
   
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.faces</url-pattern>
    </servlet-mapping>
   
    <welcome-file-list>
        <welcome-file>pages/index.jsp</welcome-file>
    </welcome-file-list>
</web-app>
这是faces-config.xml
<?xml version="1.0"?>
 <!DOCTYPE faces-config PUBLIC
 "-//Sun Microsystems, Inc.//DTD JavaServer Faces Config 1.0//EN"
 "http://java.sun.com/dtd/web-facesconfig_1_0.dtd"> <faces-config>
    <navigation-rule>
        <from-view-id>*</from-view-id>
        <navigation-case>
            <from-outcome>success</from-outcome>
            <to-view-id>pages/welcome.jsp</to-view-id>
        </navigation-case>
        <navigation-case>
            <from-outcome>failure</from-outcome>
            <to-view-id>pages/index.jsp</to-view-id>
        </navigation-case>
    </navigation-rule>
       
    <managed-bean>
        <managed-bean-name>user</managed-bean-name>
        <managed-bean-class>
            onlyfun.caterpillar.UserBean
        </managed-bean-class>
        <managed-bean-scope>session</managed-bean-scope>
    </managed-bean>
 </faces-config>
这是index.jsp文件
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@page contentType="text/html;charset=Big5"%> 
 <html>
 <head>
 <title>第一個JSF程式</title>
 </head>
 <body>
    <f:view>
    </f:view>
 </body>