struts - problema de exceptions

[estebanja]

Hola què tal, cuando corro una aplicaciòn (con el tomcat) que se basa en struts, me aparece lo siguiente:

type Informe de Excepción
mensaje
descripción El servidor encontró un error interno () que hizo que no pudiera rellenar este requerimiento.
excepción
javax.servlet.ServletException: La ejecución del Servlet lanzó una excepción
causa raíz
java.lang.NoClassDefFoundError: org/dom4j/DocumentException
PersonsManager2.init(PersonsManager2.java:56)
PersonsManager2.<init>(PersonsManager2.java:19)
SearchPersonAction3.execute(SearchPersonAction3.ja va:25)
org.apache.struts.action.RequestProcessor.processA ctionPerform(RequestProcessor.java:419)
org.apache.struts.action.RequestProcessor.process( RequestProcessor.java:224)
org.apache.struts.action.ActionServlet.process(Act ionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(Acti onServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet .java:709)
javax.servlet.http.HttpServlet.service(HttpServlet .java:802)

Los contenidos pertinentes, de los archivos son:

\\\"PersonsManager2.java\\\"

public class PersonsManager2 implements IManejadorPersonas
{

SessionFactory sessionFactory = null;


/*inicializo el marco de persistencia*/

public PersonsManager2()throws DatastoreException
{
super();
init();

}

private void init()throws DatastoreException
{
try
{
sessionFactory=new Configuration().configure().buildSessionFactory();

}catch(Exception ex){
throw DatastoreException.datastoreError(ex);
}
}



\\\"SearchPersonAction3.java\\\"

public class SearchPersonAction3 extends Action
{



public ActionForward execute(ActionMapping mapping,ActionForm form,HttpServletRequest request,HttpServletResponse response)
throws Exception
{

ActionForward forward = null;
IManejadorPersonas service = null;



try
{
String dni =((SearchPersonForm)form).getDniAccess();

service = new PersonsManager2();

.......................sigue...................... .

}catch(Exception ex)
{
ServletContext context = getServlet().getServletContext();
context.log(\\\"Problema de crear el servicio\\\");
ex.printStackTrace();
throw DatastoreException.datastoreError(ex);
//forward = mapping.findForward(\\\"failure\\\");

}

return forward;


\\\"DatastoreExeption.java\\\"

public class DatastoreException extends BaseException {

/**
* Return a DatastoreException for datastoreError condition.
*
* @return The new DatastoreException object.
*/
public static DatastoreException retrieveConstraint() {
Object[] args = {};
DatastoreException datastoreException = new DatastoreException(RETRIEVE_CONSTRAINT, args);
return (datastoreException);
}

public static DatastoreException objectNotFound() {
Object[] args = {};
DatastoreException datastoreException = new DatastoreException(OBJECTNOTFOUND_ERROR, args);
return (datastoreException);
}

public static DatastoreException datastoreError( Throwable rootCause) {
Object[] args = {};
DatastoreException datastoreException = new DatastoreException(DATASTORE_ERROR, args);
datastoreException.setRootCause( rootCause );
return (datastoreException);
}

/**
* For use by subclasses of DatastoreException.
*/
protected DatastoreException(String newErrorCode,
Object[] args) {
super(newErrorCode, args);
}
public static final String RETRIEVE_CONSTRAINT = \\\"RetrieveConstraint\\\";
public static final String DATASTORE_ERROR = \\\"DatastoreError\\\";
public static final String OBJECTNOTFOUND_ERROR = \\\"ObjectNotFound\\\";



Bueno, no sè còmo resolver este error.
Desde ya muchas gracias
Saludos