For Each item As DataListItem In DataList2.Items
            Dim b As Button = CType(item.FindControl("Button3"), Button)
            If (Not b Is Nothing) Then
                REM  If b.CommandArgument = User.Identity.Name Then 'rileva la user loggata
                If b.CommandArgument = Session.Item("iddocente") Then 'Membership.GetUser(User.Identity.Name, False).ProviderUserKey Then
                    b.Visible = True
                Else
                    b.Visible = False
                End If
            End If
        Next