Can not retrieve parameters.

edit

I am running ur5_moveit_config demo.launch from ros-industrial's universal robot package and I'd like to control it from my node. For that purpose I need to retrieve several parameters from parameter server. The first one is planning_plugin.

Calling rosparam list | grep planning_plugin gives /move_group/planning_plugin. Which means that parameter exists.

Here is my node initialization code:

#include <ros/ros.h>
#include <pluginlib/class_loader.h>

/* Moveit includes */
#include <moveit/robot_model/robot_model.h>
#include <moveit/robot_model_loader/robot_model_loader.h>
#include <moveit/planning_scene/planning_scene.h>
#include <moveit/planning_interface/planning_interface.h>
#include <moveit_msgs/DisplayTrajectory.h>
#include <moveit_msgs/PlanningScene.h>
#include <moveit/kinematic_constraints/utils.h>

#include <iostream>
#include <boost/scoped_ptr.hpp>

int main(int argc, char **argv) {
    ros::init(argc, argv, "arm_control_node");
    ros::AsyncSpinner spinner(1);
    spinner.start();
    ros::NodeHandle node_handle("/move_group/arm_control");

    std::string planner_plugin_name; //= "ompl_interface/OMPLPlanner";

    if (!node_handle.getParam("planning_plugin", planner_plugin_name)) {
        ROS_FATAL_STREAM("Could not find planner plugin name");
    }

    return 0;
}

Launching executable with rosrun arm_control arm_control_node prints [FATAL] [1508419005.957461571]: Could not find planner plugin name. However rosparam get /move_group/planning_plugin outputs ompl_interface/OMPLPlanner.

I have tried to hardcode plugin name as a result I have got an error about retrieving other parameters. It seems like the node can not get access to them but why is a mystery for me.