BaseDir / BaseURL

dear community,

due to a recent project, where i want to use ckfinder in combination with ckeditor i'm having some troubles with basedir and baseurl vars.

my filesystem:

/sandbox
* articles.php (a logic to create and edit articles)
/sandbox/ckeditor/
/sandbox/ckfinder/

to be able to use ckeditor / ckfinder in the articles.php i've sticked to the sample.php of ckfinder and modified the snippet for my use:

include_once 'ckeditor/ckeditor.php';
include_once 'ckfinder/ckfinder.php';
             
$ckeditor = new CKEditor();
$ckeditor->basePath = 'ckeditor/';
CKFinder::SetupCKEditor($ckeditor, 'ckfinder/');
$ckeditor->editor('form_content_content', $form_content_content_value);

=> that works "great"; i can access the browse / upload function of ckfinder.

but now, when i want to upload media, ckfinder puts it in the same directory as sandbox/, getting the following file system:

/ckfinder/
/sandbox
* articles.php (a logic to create and edit articles)
/sandbox/ckeditor/
/sandbox/ckfinder/

i'm trying now for several hours to get it working correctly, but without success. my goal was to upload media administrated with ckfinder into /uploads/content/:

/sandbox
* articles.php (a logic to create and edit articles)
/sandbox/ckeditor/
/sandbox/ckfinder/
/sandbox/uploads/content/

thanks in advance,
chris