Hibernate Mapping Error

I have the following Hibernate xml file:

<hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
    <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
    <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/ProgramacionAvanzada2</property>
    <property name="hibernate.connection.username">postgres</property>
    <property name="hibernate.connection.password">postgres</property>
    <mapping class="MODELO.CalendarioReservas" package="MODELO"/>
    <mapping class="MODELO.Cliente" package="MODELO"/>
    <mapping class="MODELO.DatosPersonales" package="MODELO"/>
    <mapping class="MODELO.Empleado" package="MODELO"/>
    <mapping class="MODELO.Factura" package="MODELO"/>
    <mapping class="MODELO.Habitacion" package="MODELO"/>
    <mapping class="MODELO.Hotel" package="MODELO"/>
    <mapping class="MODELO.Mesa" package="MODELO"/>
    <mapping class="MODELO.Pedido" package="MODELO"/>
    <mapping class="MODELO.Plato" package="MODELO"/>
    <mapping class="MODELO.Proveedor" package="MODELO"/>
    <mapping class="MODELO.Renglon" package="MODELO"/>
    <mapping class="MODELO.ReservaHabitacion" package="MODELO"/>
    <mapping class="MODELO.ReservaMesa" package="MODELO"/>
    <mapping class="MODELO.Servicio" package="MODELO"/>
    <mapping class="MODELO.Tarjeta" package="MODELO"/>
    <mapping class="MODELO.Usuario" package="MODELO"/>
    <mapping class="MODELO.TarjetaCredito" package="MODELO"/>
  </session-factory>
</hibernate-configuration>

This is the function that a new object tries to persist:

public void guardar(Object objeto) {
        // Abrir una sesion (conexion a la DB)
        Session sesion = miFabricaSesion.openSession();

        // Iniciar una transaccion
        sesion.getTransaction().begin();

        // Agregar un objeto a la DB
        sesion.persist(objeto);

        // Guardar los cambios
        sesion.getTransaction().commit();

        sesion.close();
    }

When I give run, I get this:

Exception in thread "AWT-EventQueue-0" org.hibernate.MappingException: Unknown entity: MODELO.TarjetaCredito
    at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:1095)
    at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1448)
    at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:242)
    at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:511)
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:116)
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:75)
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:807)
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:780)
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:785)
    at CONTROLADOR.ControladorPersistencia.guardar(ControladorPersistencia.java:52)

However, as seen above, if I have mapped my "CreditCard" class. See:

<mapping class="MODELO.TarjetaCredito" package="MODELO"/>

Would someone help me solve this error? Thanks in advance.