/**
  * Verifies if a group name is valid (for a new group)
  *
  * @param string $string - Name of the group
  * @return boolean True if the name is valid, false otherwise.
  **/
 function isValidName($string)
 {
     if ($string == "" || UserGroups_tp::groupExists($string)) {
         return false;
     }
     return true;
 }