数据超过一屏不能下拉刷新

[xaiocaiji7653]

Widget build(BuildContext context) {
return SmartRefresher(
enablePullDown: true,
enablePullUp: true,
controller: _refreshController,
onRefresh: () {
_feedController.refreshHotFeedList(_refreshController);
},
onLoading: () {
_feedController.getHotFeedList(_refreshController);
},

 child: _getInvitationList(context));

}

_getInvitationList(BuildContext context) {
return Obx(() {
List invitationList = _feedController.hotFeedList;
if (invitationList.isEmpty) {
return Container(
color: ColorRes.color_14,
height: MediaQuery.of(context).size.height,
);
} else {
return ListView.separated(
separatorBuilder: (context, index) => const Divider(
// height: 10,
thickness: 5,
color: ColorRes.color_14,
),
controller: _pageController,
itemCount: invitationList.length,
itemBuilder: (context, index) {
return Container(
height: 80,
child: Text("$index"),
);

为什么当数据不满一屏的时候可以下拉和上拉，满了就不能下拉和上拉刷新了啊