Why Can't I create an Appointment using this C# code?

Question

I have the following C# code and I'm getting an error (see below). Can anyone tell me what I am missing and why would I get an error at this point in the code?
public static void Test()
GroupwareTypeLibrary.Application groupwiseApp;
GroupwareTypeLibrary.Account groupwiseAccount;
object gwAppointment = "GW.MESSAGE.APPOINTMENT";
object _missing = System.Reflection.Missing.Value;
object egwDraft = 4;
string mypassword = "abc123";
groupwiseApp = new GroupwareTypeLibrary.Application();
groupwiseAccount = groupwiseApp.Login("", "", mypassword, 0, _missing);
//Create a New Appointment
GroupwareTypeLibrary.Appointment7 appt;
try
appt = (GroupwareTypeLibrary.Appointment7)groupwiseAccoun t.WorkFolder.Messages.Add(gwAppointment, egwDraft, _missing);
>>>>>>>>>>>> I get the following error on the line above
>>>>>>>>>>>> "Object does not match target type." Any Ideas (i.e., what "type" should I use, See below the properties of the appointment I'm trying to set) ????
catch (System.Exception ex)
MessageBox.Show("Could not create Appointment item:\r\n\r\n" + ex.Message);
return;
appt.StartDate = DateTime.Now;
appt.EndDate = DateTime.Now.AddMinutes(30);
appt.AlarmSet = false;
appt.Subject.PlainText = "This is the Subject";
string messageID = appt.MessageID.ToString();
string RetString;
string cmdOpenMessage = "ItemOpen(\"" + messageID + "\")";
GroupWiseCommander.GWCommander gwc = new GroupWiseCommander.GWCommander();
gwc.Execute(cmdOpenMessage, out RetString);
return;

Answer 1

I solved the problem. The above code works fine if used alone, but I was also using the DevExpress.XtraScheduler control, and when I updated the GroupWise calendar items using a background thread, from that point on I couldn't talk to GroupWise at all. So I've rewritten my code not to use a background thread and it appears to be working fine.