così?

codice:
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="a.aspx.vb" Inherits="prove_a" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server" >
    <div>
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True">
        </asp:DropDownList>
        <br /><br />
        <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
    </div>
    </form>
</body>
</html>
codice:
Option Strict On
Imports o = Oracle.DataAccess.Client


Partial Class prove_a
    Inherits System.Web.UI.Page


    Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        If Not Me.IsPostBack Then
            'popolo il DropDown leggendo i dati da database
            ora.FillListControl(Me.DropDownList1, gl.StringaConnessioneORA_PIETRO, "SELECT ID_REGIONE, NOME_REGIONE FROM REGIONI WHERE ID_REGIONE > 0 ORDER BY LOWER(NOME_REGIONE)", "nome_regione", "id_regione", New ListItem())
        End If
    End Sub

    Protected Sub DropDownList1_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged
        Dim c As DropDownList = DirectCast(sender, DropDownList)
        Me.PlaceHolder1.Controls.Add(New LiteralControl(String.Format("{0} - {1}", c.SelectedItem.Text, c.SelectedItem.Value)))

    End Sub
End Class