Fatal error: Uncaught Error: Class 'GridColumn' not found in C:\xampp2\htdocs\pubblicazione_protocollo\KoolControls\KoolGrid\ext\columns\GridPercentageColumn.php:3 Stack trace: #0 {main} thrown in C:\xampp2\htdocs\pubblicazione_protocollo\KoolControls\KoolGrid\ext\columns\GridPercentageColumn.php on line 3