class dijkstra_custom_visitor : public boost::default_dijkstra_visitor

{

public:

    dijkstra_threshold(glm::dvec3 source, double threshold): s(source), threshold(threshold) {}

    struct hit_threshold {};

    void examine_vertex(boost::graph_traits <unGraph>::vertex_descriptor v, const unGraph& g) {

        glm::dvec3 dest = boost::get(&VertexProperties::m_mid_point, g, v);

        if( glm::distance(s,dest) > threshold ) throw hit_threshold();

    }

    double threshold;

    glm::dvec3 s;

};

My 'calling' line is:

            std::vector<Vertex> predecessors(boost::num_vertices(m_ugraph));
            std::vector<Weight> distances(boost::num_vertices(m_ugraph), std::numeric_limits<double>::max() );


            IndexMap indexMap = boost::get(boost::vertex_index, m_ugraph);
            PredecessorMap predecessorMap(&predecessors[0], indexMap);
            DistanceMap distanceMap(&distances[0], indexMap);

            glm::dvec3 s_mid = m_ugraph[*vertex_iterator_begin].m_mid_point;
            double thres = 500.0f;

            boost::dijkstra_shortest_paths(m_ugraph, *vertex_iterator_begin, boost::predecessor_map(predecessorMap).distance_map(distanceMap).visitor(boost::make_dijkstra_visitor(dijkstra_custom_visitor(s_mid,thres))));


What do you think is the problem?
thanks