title: why multiple ng-select options doesn't work?
body: <p>Im trying to do this example with multiple choices <a href="https://stackblitz.com/edit/ng-select?file=app%2Fapp.component.ts" rel="nofollow noreferrer">https://stackblitz.com/edit/ng-select?file=app%2Fapp.component.ts</a> but it doesn't work for me. I don't know what's happening...</p>
  <p>This is my code:</p>
  <pre><code>  &lt;div class=&quot;input-group&quot;&gt;
      &lt;label htmlFor=&quot;ca&quot; class=&quot;sr-only&quot;&gt; Asignaturas:&lt;/label&gt;
      &lt;ng-select [items]=&quot;asignaturasLista&quot;
      bindLabel=&quot;name&quot;
      bindValue=&quot;id&quot;
      [multiple]=&quot;true&quot;
      placeholder=&quot;Select asignaturas&quot;
      [(ngModel)]=&quot;asignaturas&quot;&gt; 
      &lt;/ng-select&gt;
      
    &lt;/div&gt;
  
    Selected asignaturas: {{asignaturas}}
  </code></pre>
  <p>It doesn't show anything on sleected asignaturas</p>
  <p>I have this on my component:</p>
  <pre><code>      asignaturasLista  = [
      {id: 1, name: 'Álgebra'},
      {id: 2, name: 'Física'},
      {id: 3, name: 'Inglés'},
      {id: 4, name: 'Matemáticas'},
      {id: 5, name: 'Lenguaje'},
      {id: 6, name: 'Historia'}
  ];
  
    asignaturas: string[];
  </code></pre>