title: Nativescript - data not binding onTap
body: <p>At certain point on my xml file i have this:</p>
  
  <pre><code>&lt;GridLayout row="2" rowSpan="2" col="2" rows="*" columns="40,*,40" verticalAlignment="center" horizontalAlignment="right" marginRight="10"&gt;
   &lt;Label row="0" col="0" text="+" tap="onTapPlus" verticalAlignment="center" horizontalAlignment="center" style="color:black;font-family: 'Allerta Stencil', sans-serif;font-size:20px;"&gt;&lt;/Label&gt;
   &lt;Label id="" row="0" col="1" text="{{nrItemsTakeAway}}" verticalAlignment="center" horizontalAlignment="center" style="color:black;font-family: 'Allerta Stencil', sans-serif;font-size:20px;text-align:center; width:50px;"&gt;&lt;/Label&gt;
   &lt;Label row="0" col="2" text="-" tap="onTapMinus" verticalAlignment="center" horizontalAlignment="center" style="color:black;font-family: 'Allerta Stencil', sans-serif;font-size:20px;"&gt;&lt;/Label&gt;
  &lt;/GridLayout&gt;
  </code></pre>
  
  <p>So when the user taps on the + button, the onTapPlus function is called and the nrItemsTakeAway is suppose to increment...so just for testing, i did this on my onTapPlus function:</p>
  
  <pre><code>function onTapPlus(args) {
  
  const button = args.object;
  const page = button.page;
  vm.set("nrItemsTakeAway", "4");
  page.bindingContext = vm;
  </code></pre>
  
  <p>but it doesn´t work...it is not binding, what am i missing here?</p>