ERROR: Cannot load message class for...Are your messages built?

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hi, i'm trying to use this simple program to acquire an image from a ROS node (in gray-scale), convert it via cv_bridge (in order to elaborate it through OpenCV), find the middle point of some stains at the image borders and publish this poins on a topic as ROS messages. my code is the following:

#include <ros/ros.h>
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>
#include <sensor_msgs/image_encodings.h>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <vector>
#include "rd_ctrl/proc_data.h"
#include <cv.h>

using namespace std;
namespace enc = sensor_msgs::image_encodings;


rd_ctrl::proc_data points;

 ros::Publisher data_pub_; 

 static const char WINDOW[] = "Image window";

 int i;
 int accu=0, accr=0, accd=0,accl=0;
 int jd=0, jr=0, jl=0, ju=0, je=0;
 CvScalar scalarl,scalaru,scalard,scalarr;
 std::vector <int> l,d,r,u;

 int nu=0,nd=0,nl=0,nr=0;


 class ImageConverter
 {
 ros::NodeHandle nh_;
 image_transport::ImageTransport it_;
 image_transport::Subscriber image_sub_;
 image_transport::Publisher image_pub_;
 public:
 ImageConverter()
 : it_(nh_)
 {
  image_pub_ = it_.advertise("out", 1);
 image_sub_ = it_.subscribe("/vrep/visionSensorData", 1,...
 &ImageConverter::imageCb, this);

 cv::namedWindow(WINDOW);
 }

  ~ImageConverter()
 {
 cv::destroyWindow(WINDOW);
 }

 void imageCb(const sensor_msgs::ImageConstPtr& msg)
 {
  cv_bridge::CvImagePtr cv_ptr;
 try
{
  cv_ptr = cv_bridge::toCvCopy(msg, enc::BGR8);
}
catch (cv_bridge::Exception& e)
{
  ROS_ERROR("cv_bridge exception: %s", e.what());
  return;
 }

 CvMat frame= cv_ptr->image;
cvSmooth(&frame, &frame, CV_MEDIAN);
cvThreshold(&frame, &frame,200, 255,CV_THRESH_BINARY);

//boundaries scanner

//left side (1)
for(i=0;i<256;i++){

 scalarl = cvGet2D(&frame, 0, i);
if(scalarl.val[0]==0) accl++;
if((scalarl.val[0]==255)&&(accl!=0)){
 l[jl]=(i-1-accl)/2;
 jl++;
 accl=0;
 nl=1;
 }
 if((i=255)&&(accl!=0)){ 
  l[jl]=(255-accl)/2;
 nl=1;
 }

 //right side (3)
 ...
 //up side (4)
 ...

 //down side (2)
 ...

  }
  cv::imshow(WINDOW, cv_ptr->image);
  cv::waitKey(3);

  image_pub_.publish(cv_ptr->toImageMsg());
  }
  };

  int main(int argc, char** argv)
  {
  ros::init(argc, argv, "image_proc");
  ImageConverter ic;

  ros::NodeHandle n;
  data_pub_ = n.advertise<rd_ctrl::proc_data>("/data_im", 1);

  points.u=u;
  points.d=d;
  points.l=l;
  points.r=r;
  data_pub_.publish(points);

  ros::spin();
  return 0;
   }

it compiles and runs but no messages are published (the above error occurs). what could be the problem? thanks for your time!!