use correct variable: $folder instead of $folderId
[tine20] / tine20 / Felamimail / Frontend /
drwxr-xr-x   ..
-rw-r--r-- 43966 ActiveSync.php
-rw-r--r-- 7154 Http.php
-rw-r--r-- 18608 Json.php
-rw-r--r-- 709 WebDAV.php
drwxr-xr-x - WebDAV