Could not find Assembly System.ComponentModel

I'开发者_运维知识库m using Silverlight 4. I need to do grouping in my DataGrid. So I need to add add reference to System.ComponentModel. I could not find System.ComponentModel in "Add Reference". I added reference to System.ComponentModel.DataAnnotations and the added the following XMLNS in my XAML Page

xmlns:cm="clr-namespace:System.Windows.Data;assembly=System.ComponentModel"

It still says that assembly System.ComponentModel cannot be found. Can anyone please help me out?

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You may have tried to reference the wrong assembly. The System.ComponentModel assembly is not available to SL assemblies, even though some of the System.ComponentModel namespaces are (i.e. a lot of the System.ComponentModel namespaced items in SL actually reside in the System assembly).

For more info, check this MSDN page: .NET Framework Class Library for Silverlight. From there you can trace which assembly the item is in.