Checking if dates are overlapping

<pre lang="xml">public bool IsOverlapping(List <AgendaEventViewModel> viewModel, AgendaEventViewModel newItem)
        {
            bool isOverlapping = false;
            ReservationModel r = new ReservationModel(int.Parse(viewModel.id));
            if (r.Begin == r.Begin)
            {

            }

           // TODO: Check if Event is Overlapping with other events :) Dynamic RoomRules Check should implemented here


            if (viewModel.Any(m => DateTime.Parse(m.start) < DateTime.Parse( newItem.start) && DateTime.Parse(newItem.start) < DateTime.Parse(m.end) ?? DateTime.MaxValue)));
            {
                this.ShowMessage(Message.Type.Info, Resources.AgendaEvent.IsOverlapping);
            }

            return isOverlapping;
        }

public class AgendaEventViewModel
    {
        public string ReturnUrl { get; set; }

        public string id { get; set; }
        public int? funeralId { get; set; }
        public int? reservationId { get; set; }

        public int? roomId { get; set; }

        [Display(Name = "Title", ResourceType = typeof(Resources.AgendaEvent))]
        public string title { get; set; }

        [Display(Name = "Start", ResourceType = typeof(Resources.AgendaEvent))]
        public string start { get; set; }

        [Display(Name = "End", ResourceType = typeof(Resources.AgendaEvent))]
        public string end { get; set; }

        public string top { get; set; }
        public string left { get; set; }

        public List<RoomItemModel> RoomItems { get; set; }
        public List<CateringItemModel> CateringItems { get; set; }

        [Display(Name = "SeatingCapacity", ResourceType = typeof(Resources.AgendaEvent))]
        public int? SeatingCapacity { get; set; } //Max Room SeatingCapacity

        [Display(Name = "ExpectedSeatingCapacity", ResourceType = typeof(Resources.AgendaEvent))]
        public int? ExpectedSeatingCapacity { get; set; } // User Chosen
    }

<pre lang="cs">public bool IsOverlapping(AgendaEventViewModel viewModel, AgendaEventViewModel newEvent)
        {
            bool isOverlapping = false;
           // ReservationModel r = new ReservationModel(int.Parse(viewModel.id));
             DateTime? begin = DateTime.Parse(viewModel.start);
            DateTime? end = DateTime.Parse(viewModel.end);

            DateTime? begin2 = DateTime.Parse(newEvent.start);
            DateTime? end2 = DateTime.Parse(newEvent.end);
            //DateTime dataToCheck;

           // TODO: Check if Event is Overlapping with other events :) Dynamic RoomRules Check should implemented here

            if (begin ==  begin2)
            {
                this.ShowMessage(Message.Type.Info, Resources.AgendaEvent.IsOverlapping);
                isOverlapping = true;
            }

            return isOverlapping;
        }

<pre lang="cs">this.ShowMessage(Message.Type.Info, Resources.AgendaEvent.IsOverlapping);
               isOverlapping = true;