[bgl] question to induced subgraphs

Hello, I use an induced subgraph of a graph with additional user defined properties like coordinates and so on. Do I have access to this properties via the get and put functions using the indices of the subgraph or do I have to access these properties via the parent (if it is the root) resp. root of the subgraph? I tried both without the demanded success. Using the second way the results were a little bit more accurate than using the first way, but they were wrong in either case. I created the subgraph as Graph& tSubgraph = g.create_subgraph; where g is a before initialized graph. Maybe it works copying the properties to the subgraph, but that wouldn't be efficient in my opinion. Thanks in advance for your answers, Stephan