I am trying following code in model plugin to create and attach a new created link to the model.

void Load(physics::ModelPtr _parent, sdf::ElementPtr _sdf)
{

    // Store the pointer to the model
    this->model = _parent; 

    this->updateConnection = event::Events::ConnectWorldUpdateBegin(std::bind(&a_link_model::OnUpdate, this));

    hasLinkCreated = false;

}

OnUpdate()

if(true == hasLinkCreated)
{
    return;
}

this->a_link = this->model->CreateLink("link_a");

if(NULL==this->a_link)
{
   ROS_ERROR("Link for %s not found in the world", "link_a");
   return;
// something wrong ??
} 

hasLinkCreated = true;

However, the link is not existing in next line. Am I missing some conceptual stuff. I am coding for ODE (and Bullet later). The bool hasLinkCreated is making sure the createlink is attempted only once.

It prints

  ROS_ERROR("Link for %s not found in the world", "point_mass");

I am checking gazebo gui model link list to see if link was created. Please let me know if any more info is needed. This is my first question.