public static void DT2xls(System.Web.HttpResponse Response,  DataTable dt)
		{
			// exportar a xls
			Response.Clear();
			Response.Buffer= true;
			Response.AddHeader("Content-Disposition", "attachment; filename=Export.xls");
			Response.ContentType = "application/vnd.ms-excel";
			System.IO.StringWriter oStringWriter = new System.IO.StringWriter();
			System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
			System.Web.UI.WebControls.DataGrid dg = new System.Web.UI.WebControls.DataGrid();
			dg.DataSource = dt;
			dg.DataBind();
			dg.RenderControl(oHtmlTextWriter);
			Response.Write(oStringWriter);
			Response.End();
		}