问错误:system.data.rbtree‘1.1.GetNodeByIndex(Int32 userIndex)，使用VB Net和Access

EN

    For i As Integer = 0 To DataGridView2.Rows.Count - 2
        Try
            ConexionBD.Open()
            ComandoBD.Connection = ConexionBD
            ComandoBD.CommandText = "INSERT INTO Ventas (IdProducto, Fecha, Hora) VALUES (@IdProducto, @Fecha, @Hora)"
            ComandoBD.Parameters.Add("@IdProducto", OleDbType.VarChar).Value = Form2.DataGridView2.Rows(i).Cells(0).Value
            ComandoBD.Parameters.Add("@Fecha", OleDbType.DBDate).Value = Now
            ComandoBD.Parameters.Add("@Hora", OleDbType.DBTime).Value = Now.TimeOfDay
            ComandoBD.ExecuteNonQuery()

            consulta = "SELECT CantidadDisponible FROM Productos WHERE Detalle='" & DataGridView2.Rows(i).Cells(1).Value.ToString & "'"
            adaptador = New OleDbDataAdapter(consulta, ConexionBD)
            registros = New DataSet
            adaptador.Fill(registros, "Productos")
            If registros.Tables("Productos").Rows.Count() <> 0 Then
                 msgbox(registros.Tables("Productos").Rows(i).Item(0)) 'HERE IS WHERE THE ERROR IS POINTING AT
            Elseif
                 msgbox("There is no available......")  'THIS MESSAGE ITS NEVER SHOWN
            End If

            ComandoBD.Dispose()
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
        ConexionBD.Close()
    Next