title: There is no directive with "exportAs" set to "ngbDatepicker"
body: <p>I'm using angular 4, i was trying to add datepicker while i'm using
     datepicker-popup.html I'm getting error as given below. I'm not getting what kind of 
     error 
     it is. please help me out.
      <a href="https://i.stack.imgur.com/KXai9.png" rel="noreferrer"><img src="https://i.stack.imgur.com/KXai9.png" alt="enter image description here"></a></p>
  
  <p><strong>datepicker-popup.html</strong></p>
  
  <pre><code>&lt;form class="form-inline"&gt;
      &lt;div class="form-group"&gt;
          &lt;div class="input-group"&gt;
              &lt;input class="form-control" placeholder="yyyy-mm-dd" name="dp" [(ngModel)]="model" ngbDatepicker #d="ngbDatepicker"&gt;
              &lt;div class="input-group-append"&gt;
                  &lt;button class="btn btn-outline-secondary" (click)="d.toggle()" type="button"&gt;
                      &lt;img src="img/calendar-icon.svg" style="width: 1.2rem; height: 1rem; cursor: pointer;" /&gt;
                  &lt;/button&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/form&gt;
  
  &lt;hr/&gt;
  &lt;pre&gt;Model: {{ model | json }}&lt;/pre&gt;
  </code></pre>