title: How do I use visible bindings with radio button observable parameter?
body: <p>The correct radio button is selected when this page renders, but the additional inputs should appear when either "sendemail" or "sms" radio button values are selected, right?</p>
  
  <pre><code>$(function () {
      var rbViewModel = {
          qrType: ko.observable('plaintext')
      };
      ko.applyBindings(rbViewModel);
  });
  </code></pre>
  
  <p>Then my radio buttons</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;input type="radio" name="txtType" value="plaintext" data-bind="checked: qrType" /&gt;Plaintext
  &lt;input type="radio" name="txtType" value="sendemail" data-bind="checked: qrType" /&gt;Send E-mail
  &lt;input type="radio" name="txtType" value="sms" data-bind="checked: qrType" /&gt;SMS
  </code></pre>
  
  <p>And my inputs:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div data-bind="visible: qrType == 'sendemail'"&gt;&lt;input type="text" id="txtEmailSubject" placeholder="E-mail subject" /&gt;&lt;/div&gt;
  &lt;div data-bind="visible: qrType == 'sendemail'"&gt;&lt;input type="text" id="txtEmailBody" placeholder="E-mail body" /&gt;&lt;/div&gt;
  &lt;div data-bind="visible: qrType == 'sms'"&gt;&lt;input type="text" id="txtSmsMsg" placeholder="SMS body" /&gt;&lt;/div&gt;
  </code></pre>
  
  <p>Is there something wrong with the attribute on the <code>div</code> elements? I thought functions were able to be used in the visible bindings per KnockoutJS <a href="http://knockoutjs.com/documentation/visible-binding.html" rel="nofollow">documentation</a>, like this:</p>
  
  <pre><code>data-bind="visible: qrType=='sendemail'"
  </code></pre>