FCKeditor saves images in wrong place

I'm on a multisite installation and need to let FCKeditor save in /home/user/drupal/sites/domain1.com/files/userfiles/ instead of /home/user/drupal/userfiles/

FCKeditor module stay in /home/user/drupal/sites/domain1.com/module/fckeditor/

I edited /home/user/drupal/sites/domain1.com/modules/fckeditor/fckeditor/editor/filemanager/upload/php/config.php in this way:

global $Config ;

// SECURITY: You must explicitelly enable this "uploader".
$Config['Enabled'] = 'uploader' ;

// Set if the file type must be considere in the target path.
// Ex: /userfiles/image/ or /userfiles/file/
$Config['UseFileType'] = false ;

// Path to uploaded files relative to the document root.
$Config['UserFilesPath'] = '/sites/domain1.com/files/userfiles/' ;

// Fill the following value it you prefer to specify the absolute path for the
// user files directory. Usefull if you are using a virtual directory, symbolic
// link or alias. Examples: 'C:\\MySite\\userfiles\\' or '/root/mysite/userfiles/'.
// Attention: The above 'UserFilesPath' must point to the same directory.
$Config['UserFilesAbsolutePath'] = '' ;

but nothing happens, am I going to do something wrong? or isn't this the right place to define path parameters?