Private Sub dgLista_SortCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridSortCommandEventArgs) Handles dgLista.SortCommand

        Dim dt As DataTable = CType(Session("Source"), DataTable)
        Dim dv As DataView = New DataView(dt)

        ' dv.Sort = e.SortExpression
        ' dgLista.DataBind()

        Dim lastExpression As String = ""
        If ViewState("SortExpression") <> Nothing Then
            lastExpression = ViewState("SortExpression").ToString()
        End If

        Dim lastDirection As String = "asc"
        If ViewState("SortDirection") <> Nothing Then
            lastDirection = ViewState("SortDirection").ToString()
        End If

        Dim newDirection As String = "asc"
        If e.SortExpression = lastExpression Then
            newDirection = IIf((lastDirection = "asc"), "desc", "asc")
        End If

        ViewState("SortExpression") = e.SortExpression
        ViewState("SortDirection") = newDirection

        dv.Sort = e.SortExpression + " " + newDirection
        dgLista.DataBind()

    End Sub