The type 'System.Data.Services.Client.DataServiceContext' is defined in an assembly that is not referenced. You must add a reference to assembly 'Microsoft.Data.Services.Client.SL, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

I have created a VS2013 solution that contains silverlight project where I'm adding CRM REST service as service reference so that I can use the XAP in CRM 2013 to open this silverlight component.

But on build I'm getting following error.

The type 'System.Data.Services.Client.DataServiceContext' is defined in an assembly that is not referenced. 
You must add a reference to assembly 'Microsoft.Data.Services.Client.SL, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

Need immediate help.