Fatal error: Uncaught Error: Interface "PHPExcel_Writer_IWriter" not found in C:\xampp\htdocs\reporteGabriel\PHPExcel-1.8\Classes\PHPExcel\Writer\PDF.php:28 Stack trace: #0 {main} thrown in C:\xampp\htdocs\reporteGabriel\PHPExcel-1.8\Classes\PHPExcel\Writer\PDF.php on line 28