为什么本机中的值选择不绑定到fieldgroup vaadin

Question

我有一个本地选择branchStateSelect：

    branchStateSelect = new NativeSelect("State:");
    branchStateSelect.setImmediate(true);
    branchStateSelect.setWidth(COMMON_FIELD_WIDTH);
    branchStateSelect.setRequired(true);
    branchStateSelect.setNullSelectionItemId(0);
    branchStateSelect.setItemCaption(0, "--Select--");
    branchStateSelect.addValueChangeListener(fetchCityListener);

并且还有另一个原生选择：这被绑定到一个字段组

   communicationAddressStateSelect = new NativeSelect("State:");
    communicationAddressStateSelect.setRequired(true);
    communicationAddressStateSelect.setImmediate(true);
         communicationAddressStateSelect.setNullSelectionAllowed(true);

    communicationAddressStateSelect.setWidth(COMMON_FIELD_WIDTH);
    communicationAddressStateSelect.setEnabled(false);

和州选择的城市监听者：

     private ValueChangeListener fetchCityListener = new ValueChangeListener() {

    public void valueChange(ValueChangeEvent event) {
        if (event.getProperty().getValue() == null) {
                     //do nothing
        }
        else{
        communicationAddressStateSelect.setNullSelectionItemId(0l
        communicationAddressStateSelect.setItemCaption(0l,
                        "state1");
        communicationAddressStateSelect.select(0l);

                }
            }

        }}

    }
};

当我选择branchstateselect native select passAddressStateSelect中的值填充为
但绑定到fieldgroup的值为null ????为什么＆GT;＆GT;＆GT;＆GT;
我想要将值0L绑定...错误是什么