Problem with config.php to upload images

I have altered the config.php file as follows;

$Config['Enabled'] = true ;
$Config['UserFilesPath'] = '/userfiles/' ;
$Config['UserFilesAbsolutePath'] = 'http://www.my-domian.com/userfiles/' ;

However I still get the error message stating that image uploading isnt enabled and to check the config.php file.

What else do I need to do to be able to upload images?

Thanks in advance