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?

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.