PropertyChangedTrigger doesn't work - wrong namespace?

I put the following (via Expression Blend 4) in my XAML file:

<i:Interaction.Triggers>
   <ei:DataStoreChangedTr开发者_开发百科igger Binding="{Binding StatusMessage}">
   <ei:ControlStoryboardAction/>
   </ei:DataStoreChangedTrigger>
</i:Interaction.Triggers>

When building the project, Expression Blend throws following error:

The tag 'DataStoreChangedTrigger' does not exist in XML namespace 'http://schemas.microsoft.com/expression/2010/interactions

What's the issue?

Thanks!

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Sounds like you haven't added a reference to the Microsoft.Expression.Interactions.dll or if you have you haven't referenced the Blend SDK 4 version of the this dll.