RichFaces SimpleSelection doesn't work in Seam

[dxxvi]

I have 2 Seam components:

@Stateful
@Name("customerList")
public class CustomerListImpl implements CustomerList {
    @Logger
    protected Log log;

    @PersistenceContext(type= PersistenceContextType.EXTENDED)
    protected EntityManager entityManager;

    @DataModel("customers")
    protected List<Customer> customers;
    
    @In(value="customerComponents", required=false)
    protected CustomerComponents customerComponents;

    public void viewSelectedRows() {
        Iterator<Object> iterator = customerComponents.getSelection().getKeys();
        while (iterator.hasNext()) {
            Object key = iterator.next();
            customerComponents.getDataTable().setRowKey(key);
            Object customer = customerComponents.getDataTable().getRowData();
            customer = null;
        }
    }

    @SuppressWarnings("unchecked")
    public void findCustomers() {
        log.debug(null);
        customers = entityManager.createQuery("select c from Customer c").getResultList();
    }

    public void goToPanelBarItem() {
        log.debug(customerComponents.getPanelBar().getSelectedPanel());
    }

    @Destroy
    @Remove
    public void destroy() {
    }
}

@Local
public interface CustomerList {
    void viewSelectedRows();
    void findCustomers();
    void goToPanelBarItem();
    void destroy();
}

@Name("customerComponents")
@Scope(ScopeType.EVENT)
public class CustomerComponents {
    private HtmlScrollableDataTable dataTable;
    private SimpleSelection selection;
    private HtmlPanelBar panelBar;
    // ... getters & setters
}

My xhtml

<a4j:form>
    <rich:scrollableDataTable value="#{customers}" var="customer" width="70px" height="200px"
                              binding="#{customerComponents.dataTable}"
                              selection="#{customerComponents.selection}">
        <rich:column width="48px">
            <f:facet name="header">ID</f:facet>
            <h:outputText value="#{customer.id}" />
        </rich:column>
    </rich:scrollableDataTable>

    <a4j:commandLink value="View Selected Rows" action="#{customerList.viewSelectedRows}"
                     reRender="selectedRowBox" />

    <rich:panelBar binding="#{customerComponents.panelBar}" width="500">
        <rich:panelBarItem name="barItem1" label="Leverage the whole set of JSF benefits ...">
            <a4j:support event="onenter" action="#{customerList.goToPanelBarItem}"/>
            Ajax4jsf is fully integrated ...
        </rich:panelBarItem>
        <rich:panelBarItem name="barItem2" label="Add AJAX capability...">
            <a4j:support event="onenter" action="#{customerList.goToPanelBarItem}"/>
            The framework is implemented ...
        </rich:panelBarItem>
    </rich:panelBar>
</a4j:form>
<h:panelGroup id="selectedRowBox"></h:panelGroup>

When I select some rows and click View Select Rows, the iterator is always empty.

When I enter a panel bar item, the goToPanelBarItem method prints the panel bar item name (that means the JSF component bindings work).

Does anybody know why the selection doesn't work?

Thank you.