How to add header & footer when I export excel and pdf

hi, please help me to create header and footer every file that I exported in every table list

    public virtual bool PageExporting(ref dynamic doc) {
        if (IsExport("excel") || IsExport("pdf"))
        {
            // Add header dengan informasi perusahaan dan tanggal
            string header = "<div style=\"text-align: center; margin-bottom: 20px;\">";
            header += "<h2>SATO WMS - RACKS LIST</h2>";
            header += "<p>Export Date: " + DateTime.Now.ToString("dd/MM/yyyy HH:mm:ss") + "</p>";
            header += "</div>";
            header += "<hr style=\"border: 1px solid #000; margin-bottom: 20px;\" />";
            doc.Text.Append(header);
        }
        //return false; // Return false to skip default export and use Row_Export event
        return true; // Return true to use default export and skip Row_Export event
    }

but when I tried, this function was not executed

Use table tag with class ew-export