activate action server in on_activate()

nav2_dwb_controller/dwb_controller/src/dwb_controller.cpp

@@ -88,6 +88,7 @@ DwbController::on_activate(const rclcpp_lifecycle::State & state)
 {
   RCLCPP_INFO(get_logger(), "Activating");
 
+  action_server_->activate();
   planner_->on_activate(state);
   costmap_ros_->on_activate(state);
   vel_pub_->on_activate();

nav2_navfn_planner/src/navfn_planner.cpp

@@ -100,6 +100,7 @@ NavfnPlanner::on_activate(const rclcpp_lifecycle::State & /*state*/)
 
   plan_publisher_->on_activate();
   plan_marker_publisher_->on_activate();
+  action_server_->activate();
 
   return nav2_util::CallbackReturn::SUCCESS;
 }