Apparently null_property_map is write-only, so it doesn't have a get() function; I hadn't realized that. Please try dummy_property_map (from boost/property_map/property_map.hpp) instead, or if that doesn't work, static_property_map or ref_property_map from the same file.
-- Jeremiah Willcock
With dp.property("node_id", boost::dummy_property_map()); I get: "error: invalid use of void expression". with dp.property("node_id", boost::static_property_map<Graph::vertex_descriptor>()); I get: "error: no matching function call to boost::static_property_map<unsigned int>::static_property_map()" with dp.property("node_id", boost::ref_property_map<Graph::vertex_descriptor, std::string>()); I get: "error: no matching function call to boost::ref_property_map<unsigned int, std::basic_string<char>
::ref_property_map()"
Round 3 :) ? David