ragazzi ho un problema non indifferente
ho una dropdownlist che quando inserisco il record si duplica
nonostante io abbia messo me.ispostback=false
posto il codice sperando che qualke anima pia mi faccia capire dove sbaglio visto che sono sei ore cercandolo di capire da solo

codice:
 Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If Me.IsPostBack = False Then
            lista()
        End If
    End Sub
    Private Sub lista()
        Dim connessione As New System.Data.OleDb.OleDbConnection
        Dim sql As New System.Data.OleDb.OleDbCommand
        connessione.ConnectionString = "provider=Microsoft.Jet.OLEDB.4.0; " & _
      "Data Source=" & Server.MapPath("mdb-database/ok.mdb;")
        Dim selectsql As String
        selectsql = "select * from locali"
        Dim cmd As New OleDbCommand(selectsql, connessione)
        Dim adapter As New OleDbDataAdapter(cmd)
        Dim pubs As New DataSet
        pubs.Reset()
        connessione.Open()
        adapter.Fill(pubs, "locali")
        Dim row As DataRow
        For Each row In pubs.Tables("locali").Rows
            Dim newitem As New ListItem
            newitem.Text = row("locale")
            newitem.Value = row("idlocale")
            DropDownList1.Items.Add(newitem)
        Next
        connessione.Close()
        
    End Sub

    Private Sub cmd_add_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd_add.Click
        locale.Visible = True
        cmd_insert.Visible = True
    End Sub

    Private Sub cmd_insert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd_insert.Click
        Dim connessione As New System.Data.OleDb.OleDbConnection
        Dim sql As New System.Data.OleDb.OleDbCommand
        connessione.ConnectionString = "provider=Microsoft.Jet.OLEDB.4.0; " & _
      "Data Source=" & Server.MapPath("mdb-database/ok.mdb;")
        Dim selectsql As String
        selectsql = "select * from locali"
        Dim cmd As New OleDbCommand(selectsql, connessione)
        Dim adapter As New OleDbDataAdapter(cmd)
        Dim pubs As New DataSet
        connessione.Open()
        adapter.Fill(pubs, "locali")
        connessione.Close()
        Dim nuova_riga As DataRow
        nuova_riga = pubs.Tables("locali").NewRow
        nuova_riga("locale") = locale.Text
        pubs.Tables("locali").Rows.Add(nuova_riga)
        Dim added As Integer
        Dim cb As New OleDbCommandBuilder(adapter)
        adapter = cb.DataAdapter
        connessione.Open()
        added = adapter.Update(pubs, "locali")
        connessione.Close()
        locale.Visible = False
        cmd_insert.Visible = False
        If added > 0 Then
            lista()
        End If
    End Sub
End Class
aiuto ve prego