Facebook C # Sdk, Framework 3.5 and Microsoft.Contracts

I downloaded the Facebook C # SDK. I am at the point where I have the facebook token and call the method:

  var fb = new FacebookClient(token);

I get the following error:

    Could not load file or assembly 'Microsoft.Contracts, Version=1.0.0.0,  
 Culture=neutral, PublicKeyToken=736440c9b414ea16' or one of its dependencies

Any suggestions? I am using .Net Framework 3.5.
Thanks