comparison for two datetime

  start = dateTimePicker1.Value;
            end = dateTimePicker2.Value;
            AvailabilityOptions myOptions = new AvailabilityOptions();
            myOptions.RequestedFreeBusyView = FreeBusyViewType.FreeBusyMerged;
            // Return a set of free/busy times.
            GetUserAvailabilityResults freeBusyResults = service.GetUserAvailability(attendees,
                                                                                 new TimeWindow(DateTime.Now, DateTime.Now.AddDays(1)),
                                                                                AvailabilityData.FreeBusy, myOptions);
            int i = 0;
            bool flag = true;
            foreach (AttendeeAvailability availability in freeBusyResults.AttendeesAvailability)
            {
                /*    foreach (CalendarEvent calendarItem in availability.CalendarEvents)
                    {

                        if (DateTime.Compare(calendarItem.StartTime, start) < 0 && DateTime.Compare(calendarItem.EndTime, end) > 0)
                        {
                            flag = false;
                            break;
                        }
                     }
                    if (flag)
                    {
                        textBox2.Text += ("Availability information for:" + attendees[i].SmtpAddress + "\r\n" + "The meeting room state is free" + "\r\n" + "\r\n");
                    }
                    flag = true;
                */


                foreach (CalendarEvent calendarItem in availability.CalendarEvents)
                {
                    if (calendarItem.StartTime.CompareTo(start) < 0 && calendarItem.EndTime.CompareTo(end) > 0)
                        textBox2.Text += ("EndTime:" + calendarItem.EndTime + "\n\r");
                }
                i++;
            }

I have  a question in if{} blocks,is there anyting wrong for if judgement? The process don't work with if blocks.