DynaValidatorForm problem

Hi,
I'm trying to implement the Commons validator framework on my project but I am having a few problems. I am using the DynaValidatorForm to validate my forms. At the moment I am just trying to make it work on a logon form. Here are the files I'm using.
The error that I am getting at the moment is this.
2003-11-27 15:42:48,837 [ERROR] org.apache.commons.validator.Validator: reflection: org.apache.struts.validator.FieldChecks.validateRequired(java.lang.Object, org.apache.commons.validator.ValidatorAction, org.apache.commons.validator.Field, org.apache.struts.action.ActionMessages, javax.servlet.http.HttpServletRequest)
java.lang.NoSuchMethodException: org.apache.struts.validator.FieldChecks.validateRequired(java.lang.Object, org.apache.commons.validator.ValidatorAction, org.apache.commons.validator.Field, org.apache.struts.action.ActionMessages, javax.servlet.http.HttpServletRequest)
java.lang.reflect.Method java.lang.Class.getMethod0(java.lang.String, java.lang.Class[], int)
native code
java.lang.reflect.Method java.lang.Class.getMethod(java.lang.String, java.lang.Class[])
Class.java:888
boolean org.apache.commons.validator.Validator.validateFieldForRule(org.apache.commons.validator.Field, org.apache.commons.validator.ValidatorAction, org.apache.commons.validator.ValidatorResults, java.util.Map, int)
Validator.java:401
void org.apache.commons.validator.Validator.validateField(org.apache.commons.validator.Field, org.apache.commons.validator.ValidatorResults)
Validator.java:544
org.apache.commons.validator.ValidatorResults org.apache.commons.validator.Validator.validate()
Validator.java:582
org.apache.struts.action.ActionErrors org.apache.struts.validator.DynaValidatorForm.validate(org.apache.struts.action.ActionMapping, javax.servlet.http.HttpServletRequest)
DynaValidatorForm.java:151
boolean org.apache.struts.action.RequestProcessor.processValidate(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, org.apache.struts.action.ActionForm, org.apache.struts.action.ActionMapping)
RequestProcessor.java:942
void org.apache.struts.action.RequestProcessor.process(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
RequestProcessor.java:255
void org.apache.struts.action.ActionServlet.process(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
ActionServlet.java:1482
void org.apache.struts.action.ActionServlet.doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
ActionServlet.java:525
void javax.servlet.http.HttpServlet.service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
HttpServlet.java:760
void javax.servlet.http.HttpServlet.service(javax.servlet.ServletRequest, javax.servlet.ServletResponse)
HttpServlet.java:853
void com.evermind.server.http.ServletRequestDispatcher.invoke(javax.servlet.ServletRequest, javax.servlet.ServletResponse)
ServletRequestDispatcher.java:721
void com.evermind.server.http.ServletRequestDispatcher.forwardInternal(javax.servlet.ServletRequest, javax.servlet.http.HttpServletResponse)
ServletRequestDispatcher.java:306
boolean com.evermind.server.http.HttpRequestHandler.processRequest(com.evermind.server.ApplicationServerThread, com.evermind.server.http.EvermindHttpServletRequest, com.evermind.server.http.EvermindHttpServletResponse, java.io.InputStream, java.io.OutputStream, boolean)
HttpRequestHandler.java:767
void com.evermind.server.http.HttpRequestHandler.run(java.lang.Thread)
HttpRequestHandler.java:259
void com.evermind.server.http.HttpRequestHandler.run()
HttpRequestHandler.java:106
void EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run()
PooledExecutor.java:803
void java.lang.Thread.run()
Thread.java:484
-------------------------------------------------------
struts-config.xml
<form-bean name="TestLogonActionForm" type="org.apache.struts.validator.DynaValidatorForm">
<form-property name="username" type="java.lang.String"/>
<form-property name="password" type="java.lang.String"/>
</form-bean>
<action path="/testLogonForm" type="gov.ons.classifications.controller.action.TestLogonAction" name="TestLogonActionForm" validate="true" scope="request" input="/TestLogonForm.jsp">
<forward name="success" path="/TestLogonForm.jsp" />
</action>

--------------------------------------------------
validation.xml
<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE form-validation PUBLIC
"-//Apache Software Foundation//DTD Commons Validator Rules Configuration 1.0//EN"
"http://jakarta.apache.org/commons/dtds/validator_1_0.dtd">

<form-validation>


<formset>

<form name="TestLogonActionForm">
<field property="username" depends="required">
<arg0 key="title.details"/>
</field>
<field property="password" depends="required">
<arg0 key="title.details"/>
</field>
</form>
</formset>
</form-validation>

----------------------------------------------
My ActionForm
package gov.ons.classifications.controller.action;
import controller.action.BaseAction;
import gov.ons.classifications.controller.form.LoginActionForm;
import org.apache.struts.validator.DynaValidatorForm;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.action.*;
public class TestLogonAction extends Action
{
/**
* Logger object for the instance of this class
*/
private static Log logger = LogFactory.getLog(LoginAction.class);
public TestLogonAction()
{
super();
}
/**
* actionForward implementation
*/
public ActionForward execute(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws ServletException
{
logger.debug("Entering execute method of LoginAction");
DynaValidatorForm f = (DynaValidatorForm) form;
String person = (String) f.get("username");
logger.debug("Entering execute method of LoginAction ====>"+f);

return mapping.findForward("success");
}
}

Any help with this would be greatly appreciated!
Thanks!