Fatal error: Cannot access empty property

代碼整合如下：

$db = MySQL::getIns();    }}class catModel extends Model{    protected $table = 'emec_cat';    public function addCat($date){      $sql = $this->db->Autoexpr($date);      return $this->db->qurey($sql);    }} class MySQL {        static protected $Ins;        protected $res;        static function getIns(){            if(self::$Ins instanceof self){                return self::$Ins;        }            self::$Ins = new MySQL();            return self::$Ins;        }        private function __construct(){            $this->res = 1;        }        protected function __destruct(){            mysql_close($link);        }}$date = array();$date['cat_name'] = $_POST['cat_name'];$date['parent_id'] = $_POST['parent_id'] + 0;$date['intro'] = $_POST['intro'];$catMode = new catModel();$catMode->addCat($date); ?>

會出現：
Fatal error: Cannot access empty property in F:\Apache2.2\htdocs\emec\test.php on line 9
去掉基類的abstract問題依舊。
環境:
apache2.2 php5.3.5

回複內容：

代碼整合如下：

$db = MySQL::getIns();    }}class catModel extends Model{    protected $table = 'emec_cat';    public function addCat($date){      $sql = $this->db->Autoexpr($date);      return $this->db->qurey($sql);    }} class MySQL {        static protected $Ins;        protected $res;        static function getIns(){            if(self::$Ins instanceof self){                return self::$Ins;        }            self::$Ins = new MySQL();            return self::$Ins;        }        private function __construct(){            $this->res = 1;        }        protected function __destruct(){            mysql_close($link);        }}$date = array();$date['cat_name'] = $_POST['cat_name'];$date['parent_id'] = $_POST['parent_id'] + 0;$date['intro'] = $_POST['intro'];$catMode = new catModel();$catMode->addCat($date); ?>

會出現：
Fatal error: Cannot access empty property in F:\Apache2.2\htdocs\emec\test.php on line 9
去掉基類的abstract問題依舊。
環境:
apache2.2 php5.3.5

寫多了一個$

