div found wrong children

<borderlayout>
			<north size="3%" flex="true">
				<hbox widths="100%">
					<menubar id="menubar" autodrop="true" height="25px">						
						<menu label="Controlo Caixa">
							<menupopup>
								<menuitem id="openFolder" label="Abertura Caixa" />
								<menuitem id="closeFolder" label="Fecho Caixa" />
							</menupopup>
						</menu>					
					</menubar>					
					<button id="sairButton" image="/img/home.gif" label="Sair" sclass="btnToolbar" />
				</hbox>
			</north>
			<center style="overflow-y:auto">
				<div id="divCenter" />
			</center>
			<south size="3%" flex="true">
				south
			</south>
		</borderlayout>

public void onCreate$layoutForm(Event event) {
		
		List<Menu> menus = menubar.getChildren();
		for (Menu menu : menus) {
			Menupopup menupopup = menu.getMenupopup();			
			List<Component> componentList = menupopup.getChildren();
			for (Component component : componentList) {
				if (component instanceof Menuitem) {
					Menuitem menuitem = (Menuitem)component;
					final String menuItemId = menuitem.getId();
					if (menuItemId.equals("sair")) {
						menuitem.addEventListener("onClick", new EventListener() {
							public void onEvent(Event e) {
								sair();
							}
						});
					} else {						
						menuitem.addEventListener("onClick", new EventListener() {
							public void onEvent(Event e) {								
								Component component = null;
								try {
									component = divCenter.getFellow(menuItemId);
								} catch (ComponentNotFoundException cnfe) {
									log.warn("Form can be activated.");
								}
								if (component == null) {
									component = Executions.createComponents(Constantes.VIEW_FOLDER + menuItemId + Constantes.VIEW_EXTENSION, null, null);
									divCenter.appendChild(component);
								}
							}
						});
					}
				}
			}
		}
	}