problem defining map extent in version 2.0

[ScottBridwell]

When trying to define the map extent and spatial reference with the following (Silverlight 4, ESRI  Silverlight API 2):

<esri:Map.Extent>
<esri:Envelope XMin="-12632222" YMin="3824823" XMax="-12359701" YMax="4064805">
<esri:Envelope.SpatialReference>
<esri:SpatialReference WKID="102100" />
</esri:Envelope.SpatialReference>
</esri:Envelope>
</esri:Map.Extent>

I get the error:  "Could not load file or assembly 'System.Runtime.Serialization, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' or one of its dependencies. The system cannot find the file specified."

Any thoughts? Thanks.

scott

[JenniferNery]

You need to add that assembly. Right-click on your Project's References "Add Reference..", one of the .NET assemblies is called "System.Runtime.Serialization", add that to your project.