Each usergroup separate upload directory

Hi,
I´ve got several groups using the editor and each should get an own directory for upload their files.

eg
group "admin":
files/ADMIN/Images
/Flash etc
group "author":
files/AUTHOR/Images
/Flash etc

I tried to submit the name of the directory by adding "GroupPath=_testagentur" to
FCKConfig.ImageBrowserURL = FCKConfig.BasePath + 'filemanager/browser/default/browser.html?GroupPath=_testagentur&Type=Image&Connector=connectors/' + _FileBrowserLanguage + '/connector.' + _FileBrowserExtension ;
but that doesn´t work.

Any idea about that?

greets from Germany
summsel