Serialization DynaActionForm

[STRUTS SL. Mailing List]

The Struts-config.xml is as follows:

<form-bean dynamic="true" name="FormCircuitos" 
type="org.apache.struts.action.DynaActionForm" >
                        <form-property name="Clase" type="java.lang.String" />
      .
      .
      .
</form-bean>

and the catalina.out I get this error.

WARN  No puedo serializar atributo de sesi?n FormCircuitos para sesi?n 
772D050829571AEA6C6E7135C8BE60DA

        
And the question is how the serialization DynaActionForm.????????

Thanks.