При попытке зарегистрировать объект в клиентском спонсоре валится исключение:

System.Runtime.Serialization.SerializationException: Because of security restrictions, the type System.Runtime.Remoting.ObjRef cannot be accessed. ---> System.Security.SecurityException: Request failed.
at System.Security.SecurityRuntime.FrameDescSetHelper(FrameSecurityDescriptor secDesc, PermissionSet demandSet, PermissionSet& alteredDemandSet)
at System.Runtime.Serialization.FormatterServices.nativeGetSafeUninitializedObject(RuntimeType type)
at System.Runtime.Serialization.FormatterServices.GetSafeUninitializedObject(Type type)
--- End of inner exception stack trace ---

Server stack trace:
at System.Runtime.Serialization.FormatterServices.GetSafeUninitializedObject(Type type)
at System.Runtime.Serialization.Formatters.Binary.ObjectReader.ParseObject(ParseRecord pr)
at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Parse(ParseRecord pr)
at System.Runtime.Serialization.Formatters.Binary.__BinaryParser.ReadObjectWithMapTyped(BinaryObjectWithMapTyped record)
at System.Runtime.Serialization.Formatters.Binary.__BinaryParser.ReadObjectWithMapTyped(BinaryHeaderEnum binaryHeaderEnum)
at System.Runtime.Serialization.Formatters.Binary.__BinaryParser.Run()
at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, IMethodCallMessage methodCallMessage)
at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, IMethodCallMessage methodCallMessage)
at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.UnsafeDeserialize(Stream serializationStream, HeaderHandler handler)
at System.Runtime.Remoting.Channels.CoreChannel.DeserializeBinaryRequestMessage(String objectUri, Stream inputStream, Boolean bStrictBinding, TypeFilterLevel securityLevel)
at System.Runtime.Remoting.Channels.BinaryServerFormatterSink.ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)

Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
at System.Runtime.Remoting.Lifetime.ILease.Register(ISponsor obj)
at System.Runtime.Remoting.Lifetime.ClientSponsor.Register(MarshalByRefObject obj)
at WindowsClient.ClientForm.button9_Click(Object sender, EventArgs e) in c:\temp\testclientsponsor\windowsclient\clientform.cs:line 305