after a short study of the simulator and the DHT.xml i found that there is missing entry in the Overlays section. This is the ParallelPastry overlay. It is not shown under Overlays when I start from GUI. I know that this is easy to fix by changing the DHT.xml, but i just wanted to advice you about (if i can call it so) problem.
the implemented overlays and the available configurations are independent from each other. Only for a subset of implementations, there is a ready-to-use configuration file. Nevertheless, you are free to add your own ones.