timeframe 'bill_date' error

require_once APPPATH . 'third_party/Recurly215/recurly.php'; // using recurly 2.15 client lib

$subscription = new Recurly_Subscription();
$subscription->plan_code = 'access_trial';
// .. fill in more subscription info

$account = new Recurly_Account();
$account->account_code = 'npstagingac1118_1@yopmail.com';
// .. fill in more account info

$subscription->account = $account;
$subscription->create();

if ($subscription) {
 // change access_trial plan type to fffvip on renewal
 $subscription->plan_code = 'fffvip'; 
 $subscription->quantity = 1;
 
 // addons
 $addon = new Recurly_SubscriptionAddOn();
 $addon->add_on_code = 'hi';
 $addon->unit_amount_in_cents = 100;
 $addon->quantity = 1;
 $addons = array();
 $addons[] = $addon;
 $subscription->subscription_add_ons = $addons;
 
 // we believe the error is thrown from the following call.
 // i'm not able to confirm because we have a try/catch surrounding
 // the entire block of code so it's possible that the error came from another request.
 $subscription->updateAtRenewal();  
}