problems with tab item and vertical panel

[paopao]

hi, when I try to add a vertical panel into a tab item I cant do that. For example:

public void onModuleLoad() {
final Button bGuardar = new Button("Guardar");

final TabPanel vista = new TabPanel();
vista.setWidth(450);
vista.setAutoHeight(true);

final TabItem titulo = new TabItem("Alianzas");
titulo.addStyleName("pad-text");
titulo.setLayout(new FormLayout());

titulo.add(bGuardar);

vista.add(titulo);

bGuardar.addSelectionListener(new SelectionListener<ComponentEvent>() {
public void componentSelected(ComponentEvent ce) {
VerticalPanel vp = new VerticalPanel();
TextField tf= new TextField();
tf.setFieldLabel("test");
TextField tf1= new TextField();
tf1.setFieldLabel("test1");
vp.add(tf);
vp.add(tf1);
titulo.add(vp);
}
});

RootPanel.get().add(vista);
}

As a result I only can see the button but when I click the button the vertical panel cant be added to my tab panel. Is possible add vertical panel to a tab item?

Thank you for your help.

[tryanDLS]

Please post in the correct forum and format your code in CODE tags.