[Q] ArcGIS Silverlight API error while running application

[SurajKoneri]

I am creating a simple map viewer silverlight application in Visual Studio 2010 with silverlight 5SDK and ArcGIS silverlight API version 4.

Solution is building successfully when i run the application it throws an XamlParseException with message " Unknown namespace http://schemas.esri.com/arcgis/client/2009. [Line: 11 Position: 51]"

Please help me to debug the error.