protected void ddlPeriodo_SelectedIndexChanged(object sender, EventArgs e) { if (ddlPeriodo.SelectedValue != "0") { btnCargarDoc.Visible = true; Session["archivo"] = null; Session["carga"] = null; AjaxFileUpload1.Dispose(); lnkNotificar.Visible = true; } else { lnkNotificar.Visible = false; } }