The Template Directory must have follwong structure and have to contain followoing files as a minimum:
(contain image files)
Important: each subdirectory must conatin in addition an "empty" index.php, that prevents direct file access.
Examples can be found in the LEPTON template that is delivered with LEPTON package.
The structure looks like follows:
You can add some subdirectories or/and files if neccessary, for example files