php Incorrect Table Name错误

'select a.id, a.storeid,b.storename,a.device_name,a.cover_image,a.model_number,a.service_info,a.cure_info,a.notice_info,a.free_seconds,a.free_cycle,a.price,a.price_cycle,a.service_deposit,a.commission_type,a.commission_rate,a.commission_money,a.commission_min_payed,a.use_status,a.web_site,a.contacts,a.phone,a.create_time,a.cover_image_url from'
                        . tablename('weikang_device_type') . 'a left join ' . tablename('ewei_shop_store') . 'b on a.storeid = b.id  where a.uniacid =:uniacid  ORDER BY a.id DESC LIMIT ' . (($pindex - 1) * $psize) . ',' . $psize, array('uniacid' => $_W['uniacid']));