MongoDB problem

I add reference MongoDB.Bson.dll and MongoDB.Driver.dll but MongoDB.Driver.dll have reference to MongoDB.Bson and this reference can't load

code:

 public class Entity
 {
 public ObjectId Id { get; set; }
 public string Name { get; set; }
 }
      public class Entity
     {
     public ObjectId Id { get; set; }
     public string Name { get; set; }
     }
     void Start () {
     var connectionString = "mongodb://localhost";
     var client = new MongoClient(connectionString);
     var server = client.GetServer();
     var database = server.GetDatabase("localList");
     var collection = database.GetCollection<Entity>("entities");
     
     var entity = new Entity { Name = "Tom" };
     
     collection.Insert(entity);
     }

and error:

 NotImplementedException: recursionPolicy != NoRecursion not currently implemented
 System.Threading.ReaderWriterLockSlim..ctor (LockRecursionPolicy recursionPolicy)
 MongoDB.Bson.Serialization.BsonSerializer..cctor ()
 Rethrow as TypeInitializationException: An exception was thrown by the type initializer for MongoDB.Bson.Serialization.BsonSerializer
 MongoDB.Driver.Internal.MongoConnection.RunCommandAs[CommandResult] (System.String databaseName, QueryFlags queryFlags, MongoDB.Driver.CommandDocument command, Boolean throwOnError)
 MongoDB.Driver.MongoServerInstance.Ping (MongoDB.Driver.Internal.MongoConnection connection)
 Rethrow as MongoConnectionException: Unable to connect to server localhost:27017: An exception was thrown by the type initializer for MongoDB.Bson.Serialization.BsonSerializer.
 MongoDB.Driver.Internal.DirectMongoServerProxy.Connect (TimeSpan timeout, MongoDB.Driver.ReadPreference readPreference)
 MongoDB.Driver.Internal.DirectMongoServerProxy.ChooseServerInstance (MongoDB.Driver.ReadPreference readPreference)
 MongoDB.Driver.MongoServer.AcquireConnection (MongoDB.Driver.ReadPreference readPreference)
 MongoDB.Driver.MongoCollection.InsertBatch (System.Type nominalType, IEnumerable documents, MongoDB.Driver.MongoInsertOptions options)
 MongoDB.Driver.MongoCollection.Insert (System.Type nominalType, System.Object document, MongoDB.Driver.MongoInsertOptions options)
 MongoDB.Driver.MongoCollection.Insert (System.Type nominalType, System.Object document)
 MongoDB.Driver.MongoCollection.Insert[Task] (AssemblyCSharp.Task document)
 MongoDB.Driver.MongoCollection`1[AssemblyCSharp.Task].Insert (AssemblyCSharp.Task document)
 AssemblyCSharp.Dal.CreateTask (AssemblyCSharp.Task task) (at Assets/AdminAds/Scripts/Dal.cs:66)
 AssemblyCSharp.Dal..ctor () (at Assets/AdminAds/Scripts/Dal.cs:25)
 AddNew.ClickAdd () (at Assets/AdminAds/Scripts/AddNew.cs:11)
 UnityEngine.GameObject:SendMessage(String, Object, SendMessageOptions)
 UIButtonMessage:Send() (at Assets/NGUI/Scripts/Interaction/UIButtonMessage.cs:77)
 UIButtonMessage:OnClick() (at Assets/NGUI/Scripts/Interaction/UIButtonMessage.cs:56)
 UnityEngine.GameObject:SendMessage(String, Object, SendMessageOptions)
 UICamera:Notify(GameObject, String, Object) (at Assets/NGUI/Scripts/UI/UICamera.cs:644)
 UICamera:ProcessTouch(Boolean, Boolean) (at Assets/NGUI/Scripts/UI/UICamera.cs:1147)
 UICamera:ProcessMouse() (at Assets/NGUI/Scripts/UI/UICamera.cs:906)
 UICamera:Update() (at Assets/NGUI/Scripts/UI/UICamera.cs:761)

Please Help