Why aren't my cookies writting?

[eluser]dkindler[/eluser]
Would anyone happen to know why my program fails to write my cookies?

Code:

function login() {
  $this->input->set_cookie("loggedin", TRUE, 7200) or die ("failure to write cookie");
}

and

Code:

function check_global_password($global_password) {
  $pw_in_question = $this->encrypt->decode($global_password);
  $query = $this->db->get('confidentials');
  foreach ($query->result() as $pw) {
   $pw = $pw->password;
  }

  if ($pw == $pw_in_question) {
   $this->session_model->login();
  } else {
   redirect($_SERVER['HTTP_REFERER']);
  }
}

Thank you