[Solved] Selected Value of DropDownList inside GridView Header Lost on Paging in ASP.Net

i find the problem. i use the sqldatasources. change with sqldataadapter problem is fixed. thank you for support.

Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub form1_Load(sender As Object, e As EventArgs) Handles form1.Load
        If Not IsPostBack Then
            ViewState("Filter") = "ALL"
            Me.BindGrid()
        End If
    End Sub


    Private Sub BindGrid()

        If ViewState("Filter") = "ALL" Then
            sqldata.SelectCommand = "SELECT * FROM [tbl_ssf]"
        Else
            sqldata.SelectCommand = "SELECT * FROM [tbl_ssf] where ilce='" & ViewState("Filter") & "'"
        End If


        sqldata.DataBind()
        'GridView1.DataSource = sqldata
        GridView1.DataBind()
        Dim ddlCountry As DropDownList = DirectCast(GridView1.HeaderRow.FindControl("ddlCountry"), DropDownList)
        Me.BindCountryList(ddlCountry)


    End Sub


    Private Sub BindCountryList(ByVal ddlCountry As DropDownList)
        ddlCountry.Items.FindByValue(ViewState("Filter").ToString()).Selected = True
    End Sub

    Protected Sub CountryChanged(ByVal sender As Object, ByVal e As EventArgs)
        Dim ddlCountry As DropDownList = DirectCast(sender, DropDownList)
        ViewState("Filter") = ddlCountry.SelectedValue
        Me.BindGrid()
    End Sub


    Protected Sub OnPaging(sender As Object, e As GridViewPageEventArgs)
        GridView1.PageIndex = e.NewPageIndex
        Me.BindGrid()
    End Sub

End Class

 ************aspx code****

<form id="form2" runat="server">
<div>
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" AllowPaging="True"
        Font-Names="Arial" Font-Size="11pt" AlternatingRowStyle-BackColor="#C2D69B" HeaderStyle-BackColor="green"
        OnPageIndexChanging="OnPaging" DataSourceID="sqldata">
        <AlternatingRowStyle BackColor="#C2D69B"></AlternatingRowStyle>
        <Columns>
            <asp:BoundField DataField="il" HeaderText="il" />
            <asp:BoundField DataField="ilce" HeaderText="ilce" />
            <asp:TemplateField>
                <HeaderTemplate>
                    ilce
                    <asp:DropDownList ID="ddlCountry" runat="server" OnSelectedIndexChanged="CountryChanged"
                        AutoPostBack="True" AppendDataBoundItems="True" DataSourceID="sqldatacombobox"
                        DataTextField="ilce" DataValueField="ilce">
                        <asp:ListItem Text="ALL" Value="ALL"></asp:ListItem>
                    </asp:DropDownList>
                </HeaderTemplate>
                <ItemTemplate>
                    <%# Eval("ilce")%>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
        <HeaderStyle BackColor="Green"></HeaderStyle>
    </asp:GridView>
    <asp:SqlDataSource ID="sqldata" runat="server" ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString %>"
        SelectCommand="SELECT * FROM [tbl_ssf]"></asp:SqlDataSource>
    <asp:SqlDataSource ID="sqldatacombobox" runat="server" ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString %>"
        SelectCommand="SELECT DISTINCT [ilce] FROM [tbl_ssf]"></asp:SqlDataSource>
</div>
</form>