TimeZone change to UTC while creating the Appointment by EWS

I am using EWS 1.2 to send appointments. On creating or updating an Appointment, TimeZone can not be showing Tokyo Standard Time same as ExchangeServer on notification mail and it's TimeZone just be shown to UTC.
But TimeZone is showing properly When I create or update an Appointment with Outlook.
 
Could anyone help me to fix this issue?

Here is sample code to replicate the issue:

ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2010_SP2, TimeZoneInfo.FindSystemTimeZoneById("Tokyo Standard Time"));
service.Credentials = new NetworkCredential(admEmailAddress, userData.Password);
service.Url = new Uri("https://exchgtest.com/EWS/Exchange.asmx");

//Create an appointment for this user in his email box userAddress.
service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, userAddress);

Appointment newAppointment = new Appointment(service);
newAppointment.Subject = "Test Subject";
newAppointment.Body = "Test Body";
newAppointment.Start = new DateTime(2013, 03, 27, 10, 00, 0);
newAppointment.End = newAppointment.Start.AddMinutes(30);
newAppointment.RequiredAttendees.Add("test@exchgtest.com");

//Attendees get notification mail for this appointment using UTC timezone
//Here is the notification content received by attendees:
//When: Tuesday, March 27, 2013 7:00 PM-7:30 PM. UTC
newAppointment.Save(SendInvitationsMode.SendToAllAndSaveCopy);

// Pull existing appointment
string itemId = newAppointment.Id.ToString();

Appointment existingAppointment = Appointment.Bind(service, new ItemId(itemId));

//Attendees get notification mail for this appointment using UTC timezone
//Here is the notification content received by attendees:
//When: Tuesday, March 27, 2013 7:00 PM-7:30 PM. UTC
existingAppointment.Update(ConflictResolutionMode.AlwaysOverwrite, SendInvitationsOrCancellationsMode.SendToAllAndSaveCopy);