Java SE (Java Platform, Standard Edition)

I have a multi scene JavaFX 2.2 application the code is on gitHub at this linkhttps://github.com/acaicedo/JFX-MultiScreen

When the application loads each scene has a controller and the scene to be displayed is loaded in a HasMap. When you go to Scene1 I have a ComboBox built with SceneBuilder so it has a FXML id cbNav and an onAction event. when I call this code from the ComboBox I get java.lang.IndexOutOfBoundsException but when I call the code below from a Button onAction event no error is produced

  public void setData() {
  cbNav.getItems().clear();
  //cbNav.setValue(null);
  cbNav.getItems().addAll("To 2","To 3","To 4");
  cbNav.setPromptText("New Me:");
    }


     //Initializes the controller class.
    @Override
    public void initialize(URL url, ResourceBundle rb) {
    setData();
    }


  @FXML
  public void goWhere(ActionEvent e) throws Exception{

  if(cbNav.getValue()=="To 2") {
  setData();
  myController.setScreen(ScreensFramework.screen2ID);
  }
Button Code below
    @FXML
    private void goToScreen2(ActionEvent event){
    setData();
    myController.setScreen(ScreensFramework.screen2ID);
    }

So the question is how do I RESET the ComboBox after the ComboBox is selected?