Fix add_child missing

src/tests/mpi/cluster/graph_manager.hpp

@@ -50,7 +50,8 @@ public:
   {
     Simulator* m = new Simulator("m", paradevs::common::NoParameters());
     
-    models.push_back(m);    
+    models.push_back(m);
+    add_child(m);
     m->add_in_port("in");
     m->add_out_port("out");