title: How to Bind a nullable bool in VM to RadRadioButton
body: <p>I am struggling with how I go about this?  In my VM I have a <code>nullable bool</code> property that I want to bind to a Yes/No(<em>true/false</em>) <code>RadRadioButton</code>.  Can someone point me in the right direction?  </p>
  
  <p>VM</p>
  
  <pre><code>public bool? IsSDS { get; set; }
  </code></pre>
  
  <p>View</p>
  
  <pre><code>&lt;telerik:Label Content="Self Directed Support" /&gt;
  &lt;StackPanel Orientation="Horizontal"&gt;
       &lt;telerik:RadRadioButton x:Name="SelfDirectedSupportYes" Content="Yes" /&gt;
       &lt;telerik:RadRadioButton x:Name="SelfDirectedSupportNo" Content="No" /&gt;
  &lt;/StackPanel&gt;
  </code></pre>
  
  <hr>
  
  <p>EDIT</p>
  
  <p>I thought this was working but I was mistaken.  Only Yes is binding.  Below is what's on my View, <code>CreateAuthView</code>:</p>
  
  <pre><code>&lt;StackPanel Orientation="Horizontal" Margin="3" Grid.Column="1" Grid.Row="2"&gt;
     &lt;telerik:RadRadioButton x:Name="Authorization_SelfDirectedSupportYes" GroupName="SDS" Content="Yes" /&gt;
      &lt;telerik:RadRadioButton x:Name="Authorization_SelfDirectedSupportNo" GroupName="SDS" Content="No" /&gt;
  &lt;/StackPanel&gt;
  </code></pre>
  
  <p>and here is the corresponding portion on my ViewModel, <code>CreateAuthViewModel</code>:</p>
  
  <pre><code>public Authorization Authorization
  {
      get
      {
         return this.authorization;
      }
      set
      {
         if (authorization != value)
         {
            this.authorization = value;
            NotifyOfPropertyChange(() =&gt; Authorization);                    
         }
      }
  }
  </code></pre>
  
  <p>And finally the Property on my Model, <code>Authorization</code>:</p>
  
  <pre><code>public bool? SelfDirectedSupportYes
  {
     get
     {
        return this.selfDirectedIndicator;
     }
     set
     {
        this.selfDirectedIndicator = value;
        this.OnPropertyChanged();
     }
  }
  </code></pre>