Erro ao fazer uma consulta

Galera depois de muito correr atrás estou conseguindo fazer o meu formulario efetuar uma consulta no banco, porém apareceu este erro logo a baixo colocarei o codigo

ERRO

javax.servlet.ServletException: java.lang.reflect.InvocationTargetException
	org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:535)
	org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:433)
	org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
	org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:390)

root cause

java.lang.reflect.InvocationTargetException
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.commons.beanutils.PropertyUtils.setSimpleProperty(PropertyUtils.java:1789)
	org.apache.commons.beanutils.BeanUtils.copyProperty(BeanUtils.java:450)
	org.apache.commons.beanutils.BeanUtils.copyProperties(BeanUtils.java:264)
	usuario.action.UsuarioAction.buscar(UsuarioAction.java:85)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)
	org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)
	org.apache.struts.actions.LookupDispatchAction.execute(LookupDispatchAction.java:150)
	org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
	org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
	org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:390)

root cause

org.hibernate.LazyInitializationException: could not initialize proxy - no Session
	org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:57)
	org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:111)
	org.hibernate.proxy.pojo.cglib.CGLIBLazyInitializer.invoke(CGLIBLazyInitializer.java:150)
	usuario.bean.Usuario$$EnhancerByCGLIB$$ac39aa29.setIdusuario(<generated>)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.commons.beanutils.PropertyUtils.setSimpleProperty(PropertyUtils.java:1789)
	org.apache.commons.beanutils.BeanUtils.copyProperty(BeanUtils.java:450)
	org.apache.commons.beanutils.BeanUtils.copyProperties(BeanUtils.java:264)
	usuario.action.UsuarioAction.buscar(UsuarioAction.java:85)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)
	org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)
	org.apache.struts.actions.LookupDispatchAction.execute(LookupDispatchAction.java:150)
	org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
	org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
	org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:390)

DAO

public Object buscar(Class clazz, Long pk) throws Exception  
     {  
         sessao = HibernateFactory.getSession();  
         transacao = sessao.beginTransaction();  
         Usuario objt = (Usuario) sessao.load(clazz,pk);  
         transacao.commit();  
         sessao.flush();  
         sessao.close();  
         return objt;  
     }

Action

[code]
public ActionForward buscar(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {

    HttpSession session = request.getSession();
    
    UsuarioForm usuarioForm = (UsuarioForm) form;
    Usuario usuario = new Usuario();
    
    
    PersistenciaDAO persistencia = new PersistenciaDAO();     
    
    usuario = (Usuario) persistencia.buscar(Usuario.class, usuarioForm.getIdusuario());        
    
    BeanUtils.copyProperties(usuario, usuarioForm);
    
    return mapping.findForward(SUCCESS);        
            
}
[/code]

JSP

 <html:form action="usuario" focus="idusuario">            
            Id:<html:text property="idusuario"/>
            Nome:<html:text property="nome"/>
            Senha:<html:password property="senha"/>            
            <html:submit property="method" ><bean:message key="button.salvar" /></html:submit>
            <html:submit property="method" ><bean:message key="button.deletar" /></html:submit>
            <html:submit property="method" ><bean:message key="button.buscar" /></html:submit>
        </html:form>

Onde estou errando?

http://www.guj.com.br/posts/list/78781.java