Проблема с классом на php

    class Contacts extends DataBase {

   public $sql_select;

   function SQL () {
        if (!$_SESSION['lang'] or $_SESSION['lang'] == "_ru") {
            $sql = mysql_query("select id, name, status, skype, icq, email, cell, facebook from users");
        } else {
            $sql = mysql_query("select id, name".$_SESSION['lang'].", status, skype, icq, email, cell, facebook from users");
        }

        if (!$sql) {echo mysql_error();}

        $this->sql_select = $sql;
   }

   function ins_cont () {

        $sql_array = mysql_fetch_array($this->sql_select);

        do {
           $id = $sql_array['id'];
           $name = $sql_array['name'.$_SESSION['lang'].''];
           $status = $sql_array['status'];
           $skype = $sql_array['skype'];
           $icq = $sql_array['icq'];
           $email = $sql_array['email'];
           $cell = $sql_array['cell'];
           $facebook = $sql_array['facebook'];

           require'theme/contacts.php';
        } while($sql_array = mysql_fetch_array($this->sql_select));
   }
}

Выдает ошибку:

Warning: mysql_fetch_array() expects parameter 1 to be resource, null given in

Толкового ответа в Сети не нашел и не могу разобраться, как исправить.