tool tip not displayed in radschedulview

<local:ModalWindowBase x:Class="CaseAce.WinUI.Common.Presenter.View.Scheduler"
                xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:local="clr-namespace:CaseAce.WinUI.Common"
                xmlns:System="clr-namespace:System;assembly=mscorlib"
                xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
                xmlns:scheduleView="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.ScheduleView"
                xmlns:schedule="clr-namespace:Telerik.Windows.Controls.ScheduleView;assembly=Telerik.Windows.Controls.ScheduleView"
                
            <Grid>

                    <telerik:RadCalendar x:Name="calendar" Grid.Row="1" Grid.Column="0" SelectedDate="{Binding CurrentDate, ElementName=scheduleview, Mode=TwoWay}" SelectionMode="Single"
                                         DisplayDate="{Binding DisplayDate, Mode=TwoWay}" DisplayMode="{Binding DisplayMode, Mode=TwoWay}"
                                         VerticalAlignment="Top" Height="200" Width="200"/>

                        <telerik:RadScheduleView x:Name="scheduleview" Grid.Row="1" ShowAppointmentDeleteButton="False"  ShowDialog="scheduleview_ShowDialog" Grid.Column="1" Margin="0" NavigationHeaderVisibility="Collapsed" ActiveViewDefinitionIndex="2" BorderThickness="0 1 1 1" FirstVisibleTime="06:00">

                                <telerik:RadScheduleView.ResourceTypesSource>
                                <telerik:ResourceTypeCollection>
                                    <telerik:ResourceType Name="Calendar">
                                        <telerik:Resource ResourceName="Team" DisplayName="Team Calendar" />
                                    </telerik:ResourceType>
                                </telerik:ResourceTypeCollection>
                            </telerik:RadScheduleView.ResourceTypesSource>
                            <telerik:RadScheduleView.ViewDefinitions>
                                <telerik:DayViewDefinition GroupFilter="{Binding GroupFilter}" Title="Day View" />
                                <telerik:WeekViewDefinition GroupFilter="{Binding GroupFilter}" Title="Week View" FirstDayOfWeek="Monday" />
                                <WorkWeek:WorkWeekViewDefinition GroupFilter="{Binding GroupFilter}" Title="Work Week View" FirstDayOfWeek="Monday" />
                                <telerik:MonthViewDefinition GroupFilter="{Binding GroupFilter}" Title="Month View" />
                                <telerik:TimelineViewDefinition GroupFilter="{Binding GroupFilter}" Title="Timeline View" />
                            </telerik:RadScheduleView.ViewDefinitions>
                        </telerik:RadScheduleView>
                    </Grid>
                </Grid>

            </Grid>
        </local:ModalWindowBase>

        In code behind:

                    ObservableAppointmentCollection appointment = new ObservableAppointmentCollection();
                    DataSet ds = Event.EventsListByAttorneyID(AttorneyID);
                    if (ds != null & ds.Tables.Count > 0 & ds.Tables[0].Rows.Count > 0)
                    {
                        DataTable dt = ds.Tables[0];
                        foreach (DataRow dr in dt.Rows)
                        {
                            appointment.Add(new Appointment { Subject = Convert.ToString(dr["EventTypeDescription"]), Start = Convert.ToDateTime(Convert.ToString(dr["EventDate"])), End = Convert.ToDateTime(Convert.ToString(dr["EventEndDate"])) });
                        }
                    }
                    scheduleview.AppointmentsSource = appointment;
                    scheduleview.ToolTip = appointment;




    I'm using the Telerik RadScheduleView in WPF.
The appointments definitely exist in the AppointmentsSource as they are visible on all views
    I want to show the tooltip for appointments. i binded the appointments as list in code behind.
    c# tooltip not working in scheduleview..