title: two way binding not working in knockout.js
body: <p>I am trying to update the UI after chages to viewModel but it doesn't work , am I missing something ?
  <a href="http://jsfiddle.net/rdZjb/1/" rel="nofollow">http://jsfiddle.net/rdZjb/1/</a></p>
  
  <pre><code>  viewModel = {
          firstName : ko.observable("adrian") 
      }
  
      $("#button1").click(
          function ()
          {
              viewModel.firstName = "Paul";
              alert(viewModel.firstName);
          }
          )
  
      ko.applyBindings(viewModel);
  </code></pre>