Visual Studio Add-in: CodeElement2.RenameSymbol not works on Namespaces

The method CodeElement2.RenameSymbol not works on Namespaces

My code loock like this:

Sub RenameNamespaces()

    For Each aProject As EnvDTE.Project In DTE.Solution.Projects
        If aProject.CodeModel IsNot Nothing Then
            For Each elem As CodeElement In aProject.CodeModel.CodeElements
                If elem.Kind = vsCMElement.vsCMElementNamespace Then
                    Dim elm2 As CodeElement2 = CType(elem, CodeElement2)
                    elm2.RenameSymbol(GetNewName())
                End If
            Next
        End If
    Next

End Sub

I use Visual Studio 2010. What I do wrong?