CKFinder doesn't want to use StartupPath from the config

In my page a have the following code:

<?php
id=$_GET['id'];
if (!is_dir("/files/$id/"))
    if ( !@mkdir("/files/$id", 0777, true) )
        die ('Cannot create a folder');  
$finder = new CKFinder() ;
$finder->BasePath = '/ckfinder/' ;
$finder->StartupPath = "Files:/files/$id/" ;
$finder->StartupFolderExpanded = true;
$finder->SelectFunction = 'ShowFileInfo' ;
$finder->Width = '100%' ;
$finder->Create() ;
?>

All seems like in manual http://docs.cksource.com/CKFinder_2.x/D ... ion/PHP_V1
Script makes /files and /files/$id too, CKFinder — /files/ subdirectories, but doesn't change folder at startup. Actually, /files/$id is not available through CKFinder.
I also tried to make CKFinder use a directory outside DocRoot for some purposes, but CKFinder totally ignores any aliases i set in apache’s vhost config. When i set

Alias /files /var/srv/domain.com/fileupload

(directory exist, owned by apache and has 777 permissions) CKFinder creates a directory named ‘files’ in the DocRoot instead of using already prepared and available via alias.
Thanks in advance.