Firstly, did you manually check if the file is accessible? secondly I believe your request is wrongly formatted:
/**
* Create a new file download response.
*
* @param SplFileInfo|string $file
* @param string $name
* @param array $headers
* @return \Symfony\Component\HttpFoundation\BinaryFileResponse
*/
public static function download($file, $name = null, array $headers = array())
{
....
}