phpexcel problem

[eluser]Damjan[/eluser]
Now I've got following error:

Fatal error: Class 'PHPExcel_Writer_Excel2007' not found in C:\Users\Damjan\Dropbox\Projects\www\PhoneNumber\application\libraries\PHPExcel\IOFactory.php on line 141

IOFactory.php:

public static function createWriter(PHPExcel $phpExcel, $writerType = '') {
// Search type
$searchType = 'IWriter';

// Include class
foreach (self::$_searchLocations as $searchLocation) {
if ($searchLocation['type'] == $searchType) {
$className = str_replace('{0}', $writerType, $searchLocation['class']);
$classFile = str_replace('{0}', $writerType, $searchLocation['path']);

$instance = new $className($phpExcel); // line 141
if ($instance !== NULL) {
return $instance;
}
}
}

// Nothing found...
throw new Exception("No $searchType found for type $writerType");
}