only second message is sent to topic

edit

Hi! i was writing a code where is publish a simple message to an existing topic. The problem is, that only on the second time i send a message is actually heard by the topic. Making the first message non existing.

Here's the code i used:

#include "ros/ros.h"
#include "trajectory_msgs/JointTrajectory.h"

 int main(int argc, char **argv)
 {
   ros::init(argc, argv, "trajectory_test_node");
   ros::NodeHandle nh;

   ros::Rate loop_rate(0.2);
   ros::Publisher r_arm_comand_publisher = nh.advertise<trajectory_msgs::JointTrajectory>
   ("/signbot/r_arm_controller/command", 1000);

   // Create a message to send.
   trajectory_msgs::JointTrajectory msg;

  // Fill the names of the joints to be controlled.
  // Note that the vacuum_gripper_joint is not controllable.
   msg.joint_names.clear();
   msg.joint_names.push_back("r_shoulder_joint");
   msg.joint_names.push_back("r_top_arm_joint");
   msg.joint_names.push_back("r_elbow_joint");
   msg.joint_names.push_back("r_wrist_joint");
   // Create one point in the trajectory.
    msg.points.resize(1);
   // Resize the vector to the same length as the joint names.
   // Values are initialized to 0.
   msg.points[0].positions.resize(msg.joint_names.size(), 0.0);
    msg.points[0].time_from_start = ros::Duration(1.0);

   if(ros::ok())
  {
    r_arm_comand_publisher.publish(msg);

   ros::spinOnce();
   loop_rate.sleep();
   ROS_INFO_STREAM ("\n1 - command SENT:\n" << msg);
   // *****************************************************************
   r_arm_comand_publisher.publish(msg);

   ros::spinOnce();
   loop_rate.sleep();
   ROS_INFO_STREAM ("\n2 - command SENT:\n" << msg);
 }
 loop_rate.sleep();
 ROS_INFO_STREAM("\n\n\t***** SHUTTING DOWN ********\n\n");
 return 0;
}

on the terminal where i execute the program, is printed this:

on the other terminal where i use rostopic echo, is printed this:

Could someone help me? Thanks