I need to build the Constant Contact C# library against .net 3.5 because that is what we are currently using.  When I switch to 3.5 and try to build I get the following error: The type or namespace name 'Json' does not exist in the namespace 'System.Runtime.Serialization' (are you missing an assembly reference?) It can no longer find JSON under System.Runtime.Serialization.  What can I do to fix this?  This is in the Component.cs and Extensions.cs file. Thanks Mike ... View more