namespaced class property not available to class method?

Question

I've been cleaning up some outdated code and refactoring some things in an app I have. I've created the namespace Game\Player with a class called obj. I call this with use Game\Player\obj as Player;. Now, when the class is instantiated with new Player();, it seems one of the methods called during the construction isn't allowed access to one of the obj class properties. Below is the layout of the Player obj:

namespace Game\Player;

class obj{
    public static $uid;
    public static $id;
    public static $chatDefault;
    public static $domain;
    public static $data;
    ...

    public function __construct(){
        global $db, $user;

        // setting up our player data
        $sql = 'SELECT * FROM '.PLAYERS.' WHERE p_uid = '.(int) $user->data['user_id'].' ORDER BY p_last_played DESC LIMIT 1';
        $result = $db->sql_query($sql);
        $row = $db->sql_fetchrow($result);

        self::$uid = $row['p_uid'];
        self::$id = $row['p_id'];
        self::$chatDefault = $row['p_chat_default'];
        self::$data = null;
        ...

        self::populateData();
        ...
    }

    public function populateData(){
        global $db, $user;

        $sqlArray = array(
            'SELECT'    => 'r.*, cr.*',
            'FROM'      => array(
                RESEARCHES => 'r',
                CITY_RESEARCHES    => 'cr',
            ),
            'WHERE'     =>  'cr.cr_research = r.research_id AND cr.cr_user = '.self::$id.' AND cr.cr_domain = '.self::$domain,
        );
        $sql = $db->sql_build_query('SELECT', $sqlArray);
        $result = $db->sql_query($sql);
        while($row = $db->sql_fetchrow($result)){
            self::$data['researches'][] = $row;
        }
    }
}

It seems that self::populateData() is executed because I get an error from within that method saying that the variables self::$id and self::$domain used in the SQL query there are empty. I'm assuming I'm attempting to use namespaces incorrectly here somehow, but I can't figure out what I'm doing wrong.