myfacese的tree2报错，请老师们指点一下。很苦闷

如题：错误代码如下javax.servlet.ServletException: org.apache.myfaces.renderkit.html.util.DummyFormUtils.isWriteDummyForm(Ljavax/faces/context/FacesContext;)Z
javax.faces.webapp.FacesServlet.service(FacesServlet.java:152)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:97)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:144)
root cause java.lang.NoSuchMethodError: org.apache.myfaces.renderkit.html.util.DummyFormUtils.isWriteDummyForm(Ljavax/faces/context/FacesContext;)Z
org.apache.myfaces.renderkit.html.util.ExtensionsPhaseListener.writeCodeBeforeBodyEnd(ExtensionsPhaseListener.java:110)
org.apache.myfaces.renderkit.html.util.ExtensionsPhaseListener.getCodeBeforeBodyEnd(ExtensionsPhaseListener.java:96)
org.apache.myfaces.renderkit.html.util.ExtensionsPhaseListener.renderCodeBeforeBodyEnd(ExtensionsPhaseListener.java:86)
org.apache.myfaces.renderkit.html.util.ExtensionsPhaseListener.afterPhase(ExtensionsPhaseListener.java:66)
org.apache.myfaces.lifecycle.PhaseListenerManager.informPhaseListenersAfter(PhaseListenerManager.java:89)
org.apache.myfaces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:391)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:138)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:97)
org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:144)我的配置是按照官方网站搞得。web。xml内容如下
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <servlet>
<servlet-name>SpringContextServlet</servlet-name>
<servlet-class>
org.springframework.web.context.ContextLoaderServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet> <context-param>
<param-name>javax.faces.CONFIG_FILES</param-name>
<param-value>/WEB-INF/faces-config.xml</param-value>
</context-param>
<listener>
<listener-class>
org.apache.myfaces.webapp.StartupServletContextListener
</listener-class>
</listener>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>0</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.jpx</url-pattern>
</servlet-mapping> <filter>
<filter-name>MyFacesExtensionsFilter</filter-name>
<filter-class>
org.apache.myfaces.webapp.filter.ExtensionsFilter
</filter-class>
<init-param>
<param-name>maxFileSize</param-name>
<param-value>20m</param-value>
</init-param>
</filter> <filter-mapping>
<filter-name>MyFacesExtensionsFilter</filter-name>
<servlet-name>Faces Servlet</servlet-name>
</filter-mapping> <filter-mapping>
<filter-name>MyFacesExtensionsFilter</filter-name>
<url-pattern>*.jpx</url-pattern>
</filter-mapping> <welcome-file-list>
<welcome-file>index.jsp</welcome-file>
<welcome-file>index.jpx</welcome-file>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>