enabledForExceptions doesn't work

Hi all:
  I'm very new to apache xml rpc, I've went through the tutorial on apache.org. When I set enabledForExceptions to false under org.apache.xmlrpc.webserver.XmlRpcServlet in web.xml like below, but it did not work, every exception can be caught by client. why is it?
  <?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
 <servlet>
  <servlet-name>XmlRpcServlet</servlet-name>
  <servlet-class>org.apache.xmlrpc.webserver.XmlRpcServlet</servlet-class>
  <init-param>
   <param-name>enabledForExtensions</param-name>
   <param-value>true</param-value>
  </init-param>
  <init-param>
   <param-name>enabledForExceptions</param-name>
   <param-value>false</param-value>
  </init-param>
 </servlet>
 <servlet-mapping>
  <servlet-name>XmlRpcServlet</servlet-name>
  <url-pattern>/xmlrpc</url-pattern>
 </servlet-mapping>
 <welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
 <login-config>
  <auth-method>BASIC</auth-method>
 </login-config>
</web-app>




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