title: MVVM DataGrid SelectedItems can't bind
body: <p>I have Silverlight MVVM project and can't get DataGrid SelectedItems from XAML code in ViewModel...</p>
  
  <pre><code>&lt;gps:DataGrid
              ItemsSource="{Binding Nodes}"
  
              SelectedItems="{Binding Node, Mode=TwoWay}"
  
              Grid.Row="2"
              HeadersVisibility="None"
              HorizontalContentAlignment="Stretch"&gt;
              &lt;gps:DataGrid.Columns&gt;
                 ...
              &lt;/gps:DataGrid.Columns&gt;
          &lt;/gps:DataGrid&gt;
  </code></pre>
  
  <p>I get an error <code>"The property "SelectedItems" does not have an accessible setter"</code>
  How can I get this property in ViewModel?</p>