title: CheckBox does not react to unchecking
body: <p>I have 3 CheckBoxes and I want to disable/enable two of them when the other one is checked/unchecked. The first step works (if I check <code>checkBoxcaja</code>, the other two checkBoxes are disabled well, but when I uncheck <code>checkBoxcaja</code>, the other two checkBoxes don't return to their original Enabled state.</p>
  
  <p>What am I doing wrong?</p>
  
  <p>I'm a newbie in WPF.</p>
  
  <p>This is the code:</p>
  
  <pre><code>private void checkBoxcaja_Checked(object sender, RoutedEventArgs e)
  {
      if (checkBoxcaja.IsChecked == true)
      {
          checkBoxbanderola.IsEnabled = false;
          checkBoxletra.IsEnabled = false;
      }
      else if (checkBoxcaja.IsChecked == false)
      {
          checkBoxbanderola.IsEnabled = true;
          checkBoxletra.IsEnabled = true;
      }
  }
  </code></pre>
  
  <p>Thanks in advance</p>