private void createAttendee() { int newAttendeesId = DataInstance.attendeeList.Last().ID + 1; var newAttendee = new SeminarAttendee(newAttendeesId, tbName.Text, tbEmail.Text, tbPhoneNumber.Text, cbStatus.Text); DataInstance.addAttendee(newAttendee); seminarReference.Attendees.Add(newAttendee); DataInstance.addSeminarAttendees(seminarReference, DataInstance.getAttendeeByEmail(newAttendee.Email), newAttendee.Status); MessageBox.Show(newAttendee.Name + " has been registered to " + seminarReference.Title, "Successfully Registered", MessageBoxButtons.OK, MessageBoxIcon.Information); if (this.AttendeeRegistered != null) { this.AttendeeRegistered(this, new EventArgs()); } }