Mensagem de Erro Não some da tela

<f:validateLength minimum="4" > 

.... maxlength="10" validatorMessage="Campo Placa Necessário"  />

<h:inputText>
   <f:validateLength>
</h:inputText>

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

package estacionamento.bean;

import estacionamento.Cliente;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

/**
 *
 * @author rgto777
 */
@Stateless
public class ClienteFacade extends AbstractFacade<Cliente> {
    @PersistenceContext(unitName = "teste2")
    private EntityManager em;

    @Override
    protected EntityManager getEntityManager() {
        return em;
    }

    public ClienteFacade() {
        super(Cliente.class);
    }
    
}

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

package estacionamento.bean;

import estacionamento.Veiculo;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

/**
 *
 * @author rgto777
 */
@Stateless
public class VeiculoFacade extends AbstractFacade<Veiculo> {
    @PersistenceContext(unitName = "teste2")
    private EntityManager em;

    @Override
    protected EntityManager getEntityManager() {
        return em;
    }

    public VeiculoFacade() {
        super(Veiculo.class);
    }
    
}

package estacionamento.jsf;

import estacionamento.Veiculo;
import estacionamento.jsf.util.JsfUtil;
import estacionamento.jsf.util.PaginationHelper;
import estacionamento.bean.VeiculoFacade;

import java.io.Serializable;
import java.util.ResourceBundle;
import javax.ejb.EJB;
import javax.inject.Named;
import javax.enterprise.context.SessionScoped;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;
import javax.faces.model.DataModel;
import javax.faces.model.ListDataModel;
import javax.faces.model.SelectItem;


@Named("veiculoController")
@SessionScoped
public class VeiculoController implements Serializable {


    private Veiculo current;
    private DataModel items = null;
    @EJB private estacionamento.bean.VeiculoFacade ejbFacade;
    private PaginationHelper pagination;
    private int selectedItemIndex;

    public VeiculoController() {
    }

    public Veiculo getSelected() {
        if (current == null) {
            current = new Veiculo();
            selectedItemIndex = -1;
        }
        return current;
    }

    private VeiculoFacade getFacade() {
        return ejbFacade;
    }
    public PaginationHelper getPagination() {
        if (pagination == null) {
            pagination = new PaginationHelper(10) {

                @Override
                public int getItemsCount() {
                    return getFacade().count();
                }

                @Override
                public DataModel createPageDataModel() {
                    return new ListDataModel(getFacade().findRange(new int[]{getPageFirstItem(), getPageFirstItem()+getPageSize()}));
                }
            };
        }
        return pagination;
    }

    public String prepareList() {
        recreateModel();
        return "List";
    }

    public String prepareView() {
        current = (Veiculo)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "View";
    }

    public String prepareCreate() {
        current = new Veiculo();
        selectedItemIndex = -1;
        return "Create";
    }

    public String create() {
        try {
            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("VeiculoCreated"));
            return prepareCreate();
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String prepareEdit() {
        current = (Veiculo)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "Edit";
    }

    public String update() {
        try {
            getFacade().edit(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("VeiculoUpdated"));
            return "View";
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String destroy() {
        current = (Veiculo)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        performDestroy();
        recreatePagination();
        recreateModel();
        return "List";
    }

    public String destroyAndView() {
        performDestroy();
        recreateModel();
        updateCurrentItem();
        if (selectedItemIndex >= 0) {
            return "View";
        } else {
            // all items were removed - go back to list
            recreateModel();
            return "List";
        }
    }

    private void performDestroy() {
        try {
            getFacade().remove(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("VeiculoDeleted"));
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        }
    }

    private void updateCurrentItem() {
        int count = getFacade().count();
        if (selectedItemIndex >= count) {
            // selected index cannot be bigger than number of items:
            selectedItemIndex = count-1;
            // go to previous page if last page disappeared:
            if (pagination.getPageFirstItem() >= count) {
                pagination.previousPage();
            }
        }
        if (selectedItemIndex >= 0) {
            current = getFacade().findRange(new int[]{selectedItemIndex, selectedItemIndex+1}).get(0);
        }
    }

    public DataModel getItems() {
        if (items == null) {
            items = getPagination().createPageDataModel();
        }
        return items;
    }

    private void recreateModel() {
        items = null;
    }

    private void recreatePagination() {
        pagination = null;
    }

    public String next() {
        getPagination().nextPage();
        recreateModel();
        return "List";
    }

    public String previous() {
        getPagination().previousPage();
        recreateModel();
        return "List";
    }

    public SelectItem[] getItemsAvailableSelectMany() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), false);
    }

    public SelectItem[] getItemsAvailableSelectOne() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), true);
    }

    public Veiculo getVeiculo(java.lang.Long id) {
        return ejbFacade.find(id);
    }
    
    @FacesConverter(forClass=Veiculo.class)
    public static class VeiculoControllerConverter implements Converter {

        @Override
        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            VeiculoController controller = (VeiculoController)facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "veiculoController");
            return controller.getVeiculo(getKey(value));
        }

        java.lang.Long getKey(String value) {
            java.lang.Long key;
            key = Long.valueOf(value);
            return key;
        }

        String getStringKey(java.lang.Long value) {
            StringBuilder sb = new StringBuilder();
            sb.append(value);
            return sb.toString();
        }

        @Override
        public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
            if (object == null) {
                return null;
            }
            if (object instanceof Veiculo) {
                Veiculo o = (Veiculo) object;
                return getStringKey(o.getId());
            } else {
                throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: "+Veiculo.class.getName());
            }
        }

    }

}