JQuery Tree File Expand Folders

Question

regarding this SO question: "jquery file tree - folder open by default?"

i tried to get the workdaround of Bermo running...

It works but only for folders like

/images/fruit/

but not for a folder like:

/images/fruit/cherry/

This is my function call:

 function fileTree(f,a){
                $('#uploadFileTreeViewFiles a').live('click',function(event){
                    event.preventDefault();
                });
                $('#uploadFileTreeViewFiles').fileTree({ 
                    root: f,
                    script: 'dateiverwaltung/listDirectory',
                    multiFolder: false,
                    expandedFolders: [a]

f ist the rootfolder and a the folder to expand.

i have no idea how to get this working.