Class 'PHPExcel_Settings' not found [ 2.0 版本 ]

在用kartik\export\ExportMenu的时候，完全按照官网给的例子来的，结果使用的时候报错：

PHP Fatal Error – yii\base\ErrorException

Class 'PHPExcel_Settings' not found

1. in /var/www/html/108/vendor/yiisoft/yii2/di/Container.php at line 374
      }
 
        $dependencies = $this->resolveDependencies($dependencies, $reflection);
        if (empty($config)) {
            return $reflection->newInstanceArgs($dependencies);
        }
 
        if (!empty($dependencies) && $reflection->implementsInterface('yii\base\Configurable')) {
            // set $config as the last parameter (existing one will be overwritten)
            $dependencies[count($dependencies) - 1] = $config;
            return $reflection->newInstanceArgs($dependencies);
        } else {
            $object = $reflection->newInstanceArgs($dependencies);
            foreach ($config as $name => $value) {
                $object->$name = $value;
            }
            return $object;
        }
    }

请问有谁遇到过这种情况吗？？？？