Member "TextTrimming" is not recognized in Expression Blend?

Question

So I am using Silverlight 4.0 I have the following code but its giving me the following error: "The member "TextTrimming" is not recognized or is not accessible", but it works fine when I run in Visual Studio 2010.

<TextBlock Margin="0,30,28.789,50.455" TextWrapping="Wrap" TextTrimming="WordEllipsis" HorizontalAlignment="Right" Width="117" RenderTransformOrigin="0.5,0.5" UseLayoutRounding="False" d:LayoutRounding="Auto" Text="This is some text in a sticky note for the sake of making sure that the text will fit and that the user can see all the necessary details that are going to be available and stuff" LineHeight="-1" FontWeight="Normal">
<TextBlock.RenderTransform>
    <TransformGroup>
        <ScaleTransform/>
        <SkewTransform AngleX="8"/>
        <RotateTransform/>
        <TranslateTransform/>
    </TransformGroup>
</TextBlock.RenderTransform>

Answer 1

Which version of Expression Blend? Only Expression Blend 4 targets Silverlight 4 as far as I know.

Answer 2

The answer to this is to use this: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=88484825-1b3c-4e8c-8b14-b05d025e1541