I am using VS 2012 update 4.
My project is a SL 5 project.
I'm using ClientUI 11, build 206.
It's happening in VS 2012. 

I have created a new form matching an existing form. Everything works fine and displays properly until I add a UXTextBox to the form. As soon as I delete the UXTextBox, everything displays again.

Below is the sample page. As soon as I add the UXTextBox anywhere on the form, I get the above error.

<Intersoft:UXPage 	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
	xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
	xmlns:Intersoft="http://intersoft.clientui.com/schemas"
	mc:Ignorable="d"
	x:Class="MyApp.Views.Adjuster.UXPage1" 
	Title="UXPage1 Page"
	d:DesignWidth="640" d:DesignHeight="480">

	<Grid x:Name="LayoutRoot">
		<Grid.Background>
			<ImageBrush AlignmentY="Bottom" AlignmentX="Right" Stretch="None" Opacity="0.5" 
						ImageSource="/MyApp;component/Assets/Images/ProductsLarge.png">
				<ImageBrush.Transform>
					<TranslateTransform X="40" Y="40"/>
				</ImageBrush.Transform>
			</ImageBrush>
		</Grid.Background>
		<Intersoft:DockPanel Margin="10" >
			<Intersoft:StylishLabel Content="Label" Intersoft:DockPanel.Dock="Top" />
			<Intersoft:UXScrollViewer Intersoft:DockPanel.IsFillElement="True" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto">
				<Intersoft:UXStackPanel Orientation="Vertical">
					<Intersoft:UXToolBar>
						<Intersoft:UXToolGroup>
							<Intersoft:UXToolBarButton Content="ToolBarButton"/>
							<Intersoft:UXToolBarButton Content="ToolBarButton"/>
						</Intersoft:UXToolGroup>
					</Intersoft:UXToolBar>
					<Intersoft:ExpandableGroupBox Header="General">
						<Intersoft:UXStackPanel Orientation="Horizontal">
							<Intersoft:UXItemsControl>
								<Intersoft:FieldLabel >
								</Intersoft:FieldLabel>
							</Intersoft:UXItemsControl>
						</Intersoft:UXStackPanel>
					</Intersoft:ExpandableGroupBox>
				</Intersoft:UXStackPanel>
			</Intersoft:UXScrollViewer>

		</Intersoft:DockPanel>

	</Grid>
</Intersoft:UXPage>

 Also, I can several other UX data entry controls (e.g., UXCheckBox) without issue. If I add the System.Windows.Controls.TextBox, it gives me the error.