Silverlight 3引用类库的几个问题

DataContract类型需要引用 System.ServiceModel.Web
[DataContract]
[KnownType(typeof(ConnectionDisconnectionRequest))]
[KnownType(typeof(ConnectionReply))]
[KnownType(typeof(ConnectionDisconnectionNotification))]
[KnownType(typeof(TextMessage))]
[KnownType(typeof(ChatEndNotification))]

using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;这两个要分别引用

另外创建Siliverlight 类库 引用 using System.Net.Sockets;好像就无效了？