Fatal error: Uncaught Error: Class 'PHPExcel_Writer_Excel5_BIFFwriter' not found in /opt/lampp/htdocs/dhtmlxSuite_v5.1/codebase/grid-excel-php/lib/PHPExcel/Writer/Excel5/Workbook.php:63 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/dhtmlxSuite_v5.1/codebase/grid-excel-php/lib/PHPExcel/Writer/Excel5/Workbook.php on line 63