表头没固定之前一切正常，固定之后上拉顶多只能触发一次，怎么破。。

<view class="tableHeader">
  <view class="searchbar">
    <navigator url='/pages/search_drug/search_drug' class='search-navigator'></navigator>
  </view>
  <text class="title">药品信息表</text>
  <view class="divLine"></view>
  <view class="tr thColor">
    <view class="th">药品号</view>
    <view class="th">药品名</view>
    <view class="th">价格</view>
    <view class="th">库存</view>
  </view>
</view>
 <scroll-view scroll-x="true" scroll-y="true" style='height:{{tbodyHeight}}px'>   //加了表头固定只能触发一次上拉加载
  <block wx:for="{{result}}" wx:key="id">
    <view class="tr" wx:if="{{index%2==0}}">
      <view class="td">{{item.id}}</view>
      <view class="td">{{item.name}}</view>
      <view class="td">{{item.price}}</view>
      <view class="td">{{item.count}}</view>
    </view>
  </block>
</scroll-view> 
<loadingmore hasmore="{{bool}}"></loadingmore>