Failure to create a transaction failed to launch?

[meilunzhi]

$steam_id = "416040089";
$order_ids = "11986919769";
$token = "VSG8Gbut";

$trade = $tradeOffers->createTrade($steam_id);
echo $trade->getError();

var_dump($tradeOffers->getTradeOffersViaAPI(true));

$trade->addOtherItem(730, 2, $order_ids);
var_dump($trade->send());
var_dump($trade->sendWithToken($token));

PHP Fatal error: Uncaught Error: Call to a member function createTrade() on null