Show empty date value on load

Hi,

I have a RadDateTimePicker which is databound to a class object when my form loads I want to display and empty value in order that the watermark content is displayed. I also want to display a date range when the date time picker is selected and in order to do this I am setting the display range values when the main window is loaded. My problem is that I am seeing the default null value  01/01/0001 00:00:00!  How do I achieve this behavior 

<telerik:RadDateTimePicker x:Name="DeldateTime" Width="160" TimeInterval="0:30:0" DateTimeWatermarkContent="Delivery Date\Time" SelectedValue="{Binding dtDeliverDate, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnDataErrors=True}" Height="26" VerticalAlignment="Bottom" ToolTip="Delivery date - Select both Day and Time values!" TabIndex="4" IsTabStop="True"  />

Date range set on loaded event

Me.DeldateTime.SelectableDateStart = DateTime.Now.AddMonths(-3)
Me.DeldateTime.SelectableDateEnd = DateTime.Now.AddMonths(3)
Me.DeldateTime.DisplayDate = DateTime.Now

Property

Public Property dtDeliverDate() As DateTime
        Get
            Return Me.m_dtDeliverDate
        End Get
        Set(value As DateTime)
            Me.m_dtDeliverDate = value
            If IsDate(m_dtDeliverDate) Then
                Me.m_szDeliveryTime = Format(m_dtDeliverDate, "HH:mm")
            End If
            Me.SendPropertyChanged("dtDeliverDate")
        End Set
    End Property​