Form validation stange issue

[eluser]BenRob[/eluser]
I've used CI for a good couple of years and used the function a lot but for some reason its not working this time

please please please can someone help

Code:

$this->load->library('form_validation');
  $this->load->helper('cookie');

  $data = array();


  if($_POST) {
   // Set validation rules including additional validation for uniqueness
   $this->form_validation->set_rules('yourname', 'Your Name', 'trim|required');
   $this->form_validation->set_rules('youremail', 'Your Email', 'trim|required|valid_email');
   $this->form_validation->set_rules('friendname', 'Friends Name', 'trim|required');
   $this->form_validation->set_rules('friendemail', 'Friends Email', 'trim|required|valid_email');

   // Run the validation and take action
   if($this->form_validation->run()) {
    echo 'valid';
   }
  }
  else{
   echo 'problem';
  }