网上的struts+ajax的例子老报Digester的异常？

运行网上一个struts+ajax的例子，http://www.souzz.net/html/edu/Ajax/Ajax2/12814_2.html
放到myeclipse里面，用tomcat启动
老是有下面的错，请问怎么搞啊

2006-12-13 11:31:34,195 ERROR [main] digester.Digester (Digester.java:1288) - Begin event threw exception
java.lang.reflect.InvocationTargetException
。。。

这是struts-config.xml
<?xml version="1.0" encoding="ISO-8859-1" ?>

<!DOCTYPE struts-config PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 1.2//EN"
"http://jakarta.apache.org/struts/dtds/struts-config_1_2.dtd">

<struts-config>
<form-beans>
<form-bean
name="inputForm"
type="ajaxsample.SampleForm"/>
</form-beans>
<global-forwards>
<forward
name="welcome"
path="/Welcome.do"/>
</global-forwards>
<action-mappings>
<!-- Default "Welcome" action -->
<action
path="/Welcome"
forward="/index.jsp"/>

<!-- start Ajax Sample -->

<action path="/sampleajax" type="ajaxsample.SampleAction"
name="inputForm" scope="request" validate="false" input="/index.jsp">

<!-- Partial Ajax Content-->
<forward name="content1" path="/index.jsp" />
<forward name="content2" path="/index.jsp" />

</action>
<action path="/logger" type="ajaxsample.LogAction" />
</action-mappings>

<controller
processorClass="org.apache.struts.tiles.TilesRequestProcessor"/>

<message-resources parameter="MessageResources" />
<plug-in className="org.apache.struts.tiles.TilesPlugin" >
<set-property property="definitions-config"
value="/WEB-INF/tiles-defs.xml" />
<set-property property="moduleAware" value="true" />
</plug-in>

<plug-in className="org.apache.struts.validator.ValidatorPlugIn">
<set-property
property="pathnames"
value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml"/>
</plug-in>

</struts-config>