带图标的跨距在窗体内不起作用

Question

以下代码有什么问题？如果我尝试添加带有图标的跨度，则页面根本不显示，只是显示了应用程序加载器

<div class="row">
  <div class="col-md-12">
<nb-card>
  <nb-card-body>
    <nb-stepper orientation="horizontal">
      <nb-step [label]="labelOne">
        <ng-template #labelOne>First step</ng-template>
<div class="row">
  <div class="col-md-12">
    <form>
        <div class="row">
          <div class="col-sm-6">
            <div class="form-group">
              <label for="inputFirstName">First Name</label>
              <input type="text" class="form-control" id="inputFirstName" placeholder="First Name">
            </div>
          </div>
          <div class="col-sm-6">
            <span ghost class="btn btn-success with-margins form-in-tip" nbPopover="Hello, how are you today?" nbPopoverMode="hover"><nb-icon icon="star"></nb-icon></span>
            <!-- <div class="form-group">
               <span ghost class="btn btn-success with-margins form-in-tip" nbPopover="Hello, how are you today?" nbPopoverMode="hover">on hover</span>
             </div> -->
          </div>
        </div>    
      </form>
        <button nbButton disabled nbStepperNext>prev</button>
        <button nbButton nbStepperNext>next</button>
      </div>
    </div>