title: Exception: Error HRESULT E_FAIL with Microsoft LightSwitch Visual Studio 2012 RC
body: <p>I installed Visual Studio 2012 RC recently along with VS 2012 SDK and LightSwitch Extensibility Toolkit. </p>
  
  <p>this is the XAML code in my Client.Design -> TControl.XAML file </p>
  
  <pre><code>&lt;UserControl x:Class="CustomControls.Presentation.Controls.TControl"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:framework="clr-namespace:Microsoft.LightSwitch.Presentation.Framework;assembly=Microsoft.LightSwitch.Client"&gt;   
      &lt;Grid Width="Auto"&gt;
          &lt;Grid.RowDefinitions&gt;
              &lt;RowDefinition Height="100"&gt;&lt;/RowDefinition&gt;
              &lt;RowDefinition Height="40"&gt;&lt;/RowDefinition&gt;
          &lt;/Grid.RowDefinitions&gt;
          &lt;framework:ContentItemPresenter ContentItem="{Binding ChildItems[0]}" Grid.Row="0" Margin="3" /&gt;
          &lt;framework:ContentItemPresenter ContentItem="{Binding ChildItems[1]}" Grid.Row="0" Margin="3" /&gt;
      &lt;/Grid&gt;
  &lt;/UserControl&gt;
  </code></pre>
  
  <p>I cannot see the output of this XAML on the designer. Instead I see this error Message up on the designer area : </p>
  
  <pre><code>Exception: Error HRESULT E_FAIL has been returned from a call to a COM component.
  Stacktrace: 
      at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
      at MS.Internal.XcpImports.Collection_InsertValue[T](PresentationFrameworkCollection`1 collection, UInt32 index, CValue value)
      at MS.Internal.XcpImports.Collection_InsertDependencyObject[T](PresentationFrameworkCollection`1 collection, UInt32 index, DependencyObject value)
      at System.Windows.PresentationFrameworkCollection`1.InsertDependencyObject(Int32 index, DependencyObject value)
      at System.Windows.Controls.UIElementCollection.InsertInternal(Int32 index, UIElement value)
  </code></pre>
  
  <p>I strongly suspect this is has something to do with namespaces involved here and the Silverlight version. My project is set to use Silverlight version 5.</p>
  
  <p>A quick googling and 'Stackoverflowing" did reveal some general info about this error but nothing of much help. </p>
  
  <p>Any help will be greatly appreciated. </p>