Wicket why page expires when opening link in new tab?

I'm building a wicket bootsrap web application with the following specs (from pom.xml):

wicket version: 6.15.0

wicket-bootstrap-core.version: 0.9.3-SNAPSHOT

I have a base page which is the father of my other pages and adds to mark up a horizontal navigation bar on top, with key component:

BootstrapBookmarkablePageLink extends BookmarkablePageLink

This is part of my BasePage.java

public abstract class BasePage extends GenericWebPage<Void> {

private static final long serialVersionUID = 1L;
String username;

public WicketApplication getApp() {
    return WicketApplication.class.cast(getApplication());
}

public BasePage(final PageParameters parameters) {
    super(parameters);

    // Read session data
    cachedUsername = (String)
BasicAuthenticationSession.get().getAttribute("username");

    // create navbar
    add(newNavbar("navbar"));

}

/**
 * @return application properties
 */
public Properties getProperties() {
    return WicketApplication.get().getProperties();
}

/**
 * creates a new {@link Navbar} instance
 *
 * @param markupId
 * The components markup id.
 * @return a new {@link Navbar} instance
 */

protected Navbar newNavbar(String markupId) {
    Navbar navbar = new Navbar(markupId) {
        private static final long serialVersionUID = 1L;

        @Override
        protected TransparentWebMarkupContainer newCollapseContainer(String  
componentId) {
            TransparentWebMarkupContainer container = 
super.newCollapseContainer(componentId);
            container.add(new CssClassNameAppender("bs-navbar-collapse"));
            return container;
        }
    };

    navbar.setPosition(Navbar.Position.TOP);
    // navbar.setInverted(true);

    NavbarButton<Void> myTab = new NavbarButton<Void>(MyPage.class, new  
PageParameters().add("name", "")
            .add("status", "All").add("date", ""), Model.of("My page"));
    NavbarButton<Void> myOtherTab = new NavbarButton<Void>
(MyOtherPage.class, new PageParameters().add("status", "initial")
            .add("date", ""), Model.of("My other page"));


navbar.addComponents(NavbarComponents.transform(
Navbar.ComponentPosition.LEFT, 
myTab, myOtherTab));

    return navbar;
}
}

Then, MyPage renders a filter form, an html table, ajaxbuttons and some links, Some of my components are ajax components:

public class MyPage extends BasePage {
private static final long serialVersionUID = 5772520351966806522L;
@SuppressWarnings("unused")
private static final Logger LOG = LoggerFactory.getLogger(MyPage.class);
private static final Integer DAYS = 270;

private DashboardFilteringPageForm filteringForm;
private CityInitialForm ncForm;
private String CityName;
private String startDate;
private CitysTablePanel citysTable;
private WebMarkupContainer numberOfNodes;

public MyPage(PageParameters parameters) throws ParseException {
    super(parameters);

    // get Citys list from repo
    final List<City> repoCitys = (List<City>) methodToGetCities();

    // select number of nodes
    numberOfNodes = new WebMarkupContainer("numberOfNodes") {
        private static final long serialVersionUID = 5772520351966806522L;
    };
    numberOfNodes.setOutputMarkupId(true);

    ncForm = new CityInitialForm("ncForm");

    // validation
    add(new FeedbackPanel("feedbackPanel")).setOutputMarkupId(true);
    ncForm.getNumberField().setRequired(true);

    ncForm.add(new AjaxButton("ncButton") {
        private static final long serialVersionUID = -6846211690328190809L;

        @Override
        protected void onInitialize() {
            super.onInitialize();
            add(newAjaxFormSubmitBehavior("change"));
        }

        @Override
        protected void onSubmit(AjaxRequestTarget target, Form<?> form) {

            // redirect to other page

        }

        @Override
        protected void updateAjaxAttributes(AjaxRequestAttributes 
attributes) {
            super.updateAjaxAttributes(attributes);
            attributes.getAjaxCallListeners().add(new 
DisableComponentListener(citysTable));
        }

    });

    numberOfNodes.add(ncForm);

    // filters
    CityName = parameters.get("name").toString() == null ? "" : 
parameters.get("name").toString();
    startDate = parameters.get("date").toString();

    filteringForm = new DashboardFilteringPageForm("filteringForm") {
        private static final long serialVersionUID = -1702151172272765464L;
    };

    // initialize form inputs
    filteringForm.setCityName(CityName);
    try {
        filteringForm.setStartDate(new SimpleDateFormat("EE MMM dd HH:mm:ss 
z yyyy", Locale.ENGLISH)
                .parse(getStartDate().equals("") ? 
CortexWebUtil.subtractDays(new Date(), DAYS).toString() : getStartDate()));
    } catch (Exception e) {
        setResponsePage(SignInPage.class, new PageParameters());
    }

    filteringForm.add(new AjaxButton("button") {
        private static final long serialVersionUID = -6846211690328190809L;

        @Override
        protected void onInitialize() {
            super.onInitialize();
            add(newAjaxFormSubmitBehavior("change"));
        }

        @Override
        protected void onSubmit(AjaxRequestTarget target, Form<?> paForm) {
            // retrieve Citys
            filterCitysAjax(target, "All");
        }

        @Override
        protected void updateAjaxAttributes(AjaxRequestAttributes 
attributes) {
            super.updateAjaxAttributes(attributes);
            attributes.getAjaxCallListeners().add(new 
DisableComponentListener(citysTable));
        }

    });

    filteringForm.getCityNameTextField().add(new OnChangeAjaxBehavior() {

        private static final long serialVersionUID = 1468056167693038096L;

        @Override
        protected void onUpdate(AjaxRequestTarget target) {
            try {
                filterCitysAjax(target, "All");
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }

        }

        @Override
        protected void updateAjaxAttributes(AjaxRequestAttributes 
attributes) {
            super.updateAjaxAttributes(attributes);
            attributes.getAjaxCallListeners().add(new 
DisableComponentListener(citysTable));
        }
    });

    // new City link
    AjaxLink<Void> newCityLink = newCityLink("newCity", repoCitys);

    // Citys table
    citysTable = new CitysTablePanel("CitysTable", repoCitys);
    citysTable.setOutputMarkupId(true);

    // add components
    add(filteringForm, newCityLink, numberOfNodes, citysTable);

}


private void filterCitysAjax(AjaxRequestTarget target, String status) {

    methodToFilterResults();

    //  re-render table component 
    CitysTablePanel cityTableNew = new CitysTablePanel("CitysTable", citys);
    cityTableNew.setOutputMarkupId(true);
    cityTableNew.setVisibilityAllowed(true);
    cityTableNew.setVisible(true);
    citysTable.replaceWith(cityTableNew);
    target.add(cityTableNew);
    citysTable = cityTableNew;
    target.appendJavaScript(CortexWebUtil.TABLE_ODD_EVEN_ROWS);

}

private AjaxLink<Void> newCityLink(String string, final List<City> Citys) {

    final AjaxLink<Void> newCityLink = new AjaxLink<Void>(string) {
        private static final long serialVersionUID = -5420108740617806989L;

        @Override
        public void onClick(final AjaxRequestTarget target) {
                numberOfNodes.add(new AttributeModifier("style", 
"display:block"));
                target.add(numberOfNodes);
        }
    };

    // new City image
    Image newCityImage = new Image("newCityIcon", new 
ContextRelativeResource("/img/new_City_icon.png"));
    add(newCityLink);
    newCityLink.add(newCityImage);

    return newCityLink;

}

}

So MyPage works but when I open MyOtherPage Link in an a new tab and trigger an ajax component in MyPage (e.g the AjaxButton) then I get the page expirtaion error.

Why is that happening? Do I need to use stateless pages? ( stateless link )

Why would it be so ard in wicket to open links in new tabs and use ajax components? I must be missing sometthing..