Zk Framework - Dynamic Tabpanel Error

Question

Good night!!!

I’m trying to make a dynamic tabpanel, when I click on the clients bar menu, it opens a clients tab with the items (textbox, combobox, etc). More is not working.You are returning the error
Sourced file: inline Evaluation of: tabCad("impathoz . . . '' : Attempt to resolve method: appendChild() on undefined variable or class name: fbTabPanels : at Line: 105 : in file: inline evaluation of: private v . . . '' : fbTabPanels . appendchild ( fbTabPanel )

'''

    <!--<zscript src="/lib/bdados.java">
    </zscript>-->


    <window id="janPrincipal" title="SisFraldas" border="normal" position="center" sizable="true" maximizable="true" minimizable="true" closable="false" width="100%">



            <zscript>
                private void bmOnClientInfo(ClientInfoEvent bmEvt) {
                    bm_ResTelaW = bmEvt.getScreenWidth();
                    bm_ResTelaH = bmEvt.getScreenHeight();


                    <![CDATA[

                    ]]>
                }

                private void bmJanPrincipalClose() {
                    desktop.getWebApp().removeAttribute("bm_Usuario_"+desktop.getId());
                    desktop.getWebApp().removeAttribute("bm_Exec_"+desktop.getId());

                    bmGeraLogs(bm_Usuario, "Login", "of", 0);
                    try {
                        bm_Con.close();
                        bm_Con = null;

                    } catch (fbEs) {
                        //
                    }
                    Executions.sendRedirect("http://www.uol.com.br");                       
                }
            </zscript>

            <zscript>
                    ArrayList bm_Janelas = new ArrayList();
                    EventListener fbOnNotify = new EventListener() {
                        public void onEvent(Event fbEvento) {
                            tabCad(fbEvento.getData());
                        }
                    };
                janPrincipal.addEventListener("onNotify",fbOnNotify);
            </zscript>
      
        <menubar>
            <menu label="Principal" >
              <menupopup>
                    <menuitem label="Clientes">
                        <attribute name="onClick">
                            tabCad("impathoz");
                        </attribute>
                    </menuitem>
              </menupopup>                
            </menu>
        </menubar>
     <!-- <vbox/> -->
      
      
            <zscript>
                private void tabCad(String arg) {
                    <![CDATA[
                        if (janPrincipal.getFellowIfAny("tabBoxPrincipal") == null) {
                            fbTabBox = new Tabbox();
                            fbTabBox.setId("tabBoxPrincipal");
                            fbTabBox.width = "100%";

                            fbTabs = new Tabs();
                            fbTabs.setId("tabsCad");
                            fbTabBox.appendChild(fbTabs);

                            fbTabPanels = new Tabpanels();
                            fbTabPanels.setId("tabpanels");
                            fbTabBox.appendChild(fbTabPanels);
                            

                            janPrincipal.appendChild(fbTabBox);
                            fbTabs.align = "center";
                        } else {
                            fbTabs = janPrincipal.getFellow("tabsCad");
                            fbTabPanels =  janPrincipal.getFellow("tabpanels");
                        }
                        
                        
                        
                        

    ////////////////////////
                        if (arg.equals("impathoz")) {
                            fbTabImpDados = "tabImpDados";
                            if (janPrincipal.getFellowIfAny(fbTabImpDados) == null) {
                                fbTabPanel = new Tabpanel();
                                fbImpDados = Executions
                                    .createComponents("/conprodutovendido.zul",null,null);

                                bm_Janelas.add("janCadBDados");

                                fbTabPanel.appendChild(fbImpDados);
                                fbTabPanels.appendChild(fbTabPanel);

                                fbTab = new Tab();
                                fbTab.setLabel("Imp.Athoz");
                                fbTab.setId(fbTabImpDados);

                                EventListener fbOnSelect = new EventListener() {
                                    public void onEvent(Event fbEvento) {
                                        Events.sendEvent(
                                            new Event("onNotify",janCadBDados,null));
                                    }
                                };

                                fbTab.addEventListener("onSelect",fbOnSelect);
                                fbTabs.appendChild(fbTab);
                            }
                            tabImpDados.selected = true;
                            Events.sendEvent(new Event("onNotify",janCadBDados,null));
                        }                           
                    ]]>
                }
            </zscript>              
      

    </window>

[ '''