hey guys

recently i managed to write a class for my stories , and everything is fine , unless counter field that stores page's hits

here is my class :

class nk_posts
{

    var $data = array();


    public function _data() {

        global $db;

        $result = $db->sql_query("
        SELECT  bt_stories.*,
        bt_tags.*,
        bt_topics.*,
        group_concat(DISTINCT bt_tags.tag ) as mytags,
        group_concat(DISTINCT bt_topics.topicname ) as mytopics
        FROM bt_stories,bt_tags,bt_topics
        WHERE 
        CONCAT( ' ', bt_stories.tags, ' ' )
        LIKE CONCAT( '%', bt_tags.tid, '%' ) 
        AND
        CONCAT( ' ', bt_stories.associated, ' ' )
        LIKE CONCAT( '%', bt_topics.topicid, '%' ) 
        AND
        time<=now() AND  section='news' AND approved='1'
        GROUP BY bt_stories.sid
        ORDER BY bt_stories.sid DESC
        ");



        while ($this->data = $db->sql_fetchrow($result)) {

            $this->sid          =  $this->data['sid'];
            $this->title        =  $this->data['title'];
            $this->counter          =  $this->data['counter'];
            //------Rest of Fields ------

            $this->_output();
        }

        }



    public function _output() {

        themeindex(
        $this->sid,
        $this->title,
        $this->counter,
        //------Rest of Fields ------

        );


    }


    }

problem

this class can't show counter filed value , but if i change counter field name to other thing like hit , .. everything goes fine

im sure its okay if i write it in normal php mysql way , but i need this to be in OOP way

any comment why it's sensitive to counter field name ?!