Cannot add item to DropDownList in Setter property in ASP .NET

Question

I'm trying to add an item to a DropDownList in a Setter, and the added item doesn't stay.

I have confirmed that Viewstate is correctly enabled as suggested in this question (http://stackoverflow.com/questions/445222/switched-to-asp-net-3-5-dropdownlist-doesnt-remember-dynamically-added-items)

Here is my code.

    Private Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
        If ddlCountry.Items.Count < Country.GetList.Length Then
            ddlCountry.DataSource = Country.GetList()
            ddlCountry.DataBind()
            'At this point, there are correctly 231 items in ddlCountry.'
        End If
    End Sub

    Public WriteOnly Property Country() As String
        Set(ByVal Value As String)
            If ddlCountry.Items.FindByValue(Value.Country) Is Nothing Then
                Dim li As New ListItem(Value.Country, Value.Country)
                ddlCountry.Items.Insert(0, li)
                ddlCountry.SelectedIndex = ddlCountry.Items.IndexOf(li)
                'At this point, there are correctly 232 items in ddlCountry'
            Else
                ddlCountry.SelectedValue = Value.Country
            End If
        End Set
    End Property

    Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
        If ddlCountry.Items.FindByText("<-- Please Select-->") Is Nothing Then
             'At this point, we are incorrectly'
             'back to 231 items - this is the problem.'
             ddlCountry.Items.Insert(0, New ListItem("<-- Please Select-->", ""))
        End If
    End Sub

Answer 1

Have tried to set the AppendDataBoundItems property to true on the dropdownlist?