I'm using ROS kinetic with UBUNTU 4.13.0-45-generic x86_64. When I run the following code, the callback method (void poseHandler::poseHandlerCallBack(const turtlesim::PoseConstPtr& posePtrNew)) is not invoked. What am I doing wrong?

edit

#include <ros ros.h=""> #include <turtlesim pose.h=""> #include <geometry_msgs twist.h=""> #include <std_srvs empty.h=""> #include <signal.h> #include <termios.h> #include <stdio.h>

float initialX;
float initialY;
float initialTheta;

class poseHandler
{
    public:
        poseHandler();
        turtlesim::PoseConstPtr currPosePtr;
        turtlesim::Pose currPose;
        void printPose();
        void poseHandlerCallBack(const turtlesim::PoseConstPtr& posePtrNew);
};
poseHandler::poseHandler()
{
}
void poseHandler::printPose()
{
    ROS_INFO("x=%f,y=%f", currPose.x, currPose.y);
    ROS_INFO("y=%f,", currPose.y);
    ROS_INFO("theta=%f,", currPose.theta);
    ROS_INFO("lin_vel=%f,", currPose.linear_velocity);
    ROS_INFO("ang_vel%f\n", currPose.angular_velocity);
}
void poseHandler::poseHandlerCallBack(const turtlesim::PoseConstPtr& posePtrNew)
{
    currPosePtr = posePtrNew;
    currPose.x = currPosePtr->x;
    currPose.y = currPosePtr->y;
    currPose.theta = currPosePtr->theta;
    currPose.linear_velocity = currPosePtr->linear_velocity;
    currPose.angular_velocity = currPosePtr->angular_velocity;

    ROS_INFO("poseHandlerCallBack!\n");
}
int main(int argc, char** argv)
{
    poseHandler pH;
    ros::init(argc, argv, "draw_ractangle");
    ros::NodeHandle nh;
    ros::Subscriber pose_sub = nh.subscribe<turtlesim::Pose>
        ("/turtlesim/turtle1/pose",1000,
         &poseHandler::poseHandlerCallBack, &pH);

    initialX = pH.currPose.x;
    initialY = pH.currPose.y;
    initialTheta = pH.currPose.theta;
    pH.printPose();

    ros::Publisher twist_pub = nh.advertise<geometry_msgs::Twist>
      ("turtle1/cmd_vel", 100);

    ros::Rate loop_rate(1);
    geometry_msgs::Twist twist_obj;

    twist_pub.publish(twist_obj);

    while(ros::ok())
    {
        ROS_INFO("target = %f", (initialX+2));
        if(pH.currPose.x < (initialX + 2))
        {
            twist_obj.linear.x = 0.4;
            twist_obj.angular.z = 0.0;
            ROS_INFO("Turtle move forward\n");
        }
        else
        {
            twist_obj.linear.x = 0.0;
            twist_obj.angular.z = 0;
            ROS_INFO("Turtle Stopped\n");
        }
        pH.printPose();
        twist_pub.publish(twist_obj);
        loop_rate.sleep();
        ros::spinOnce();
        ROS_INFO("spinOnce() called\n");
    }
}