Php 通过Salesforce API创建新的定期捐赠时出现的问题

最近我遇到了如下所述的错误：

错误：无法\u插入\u更新\u激活\u实体 消息：npe03.RecurringInvestment:执行AfterInsert的原因：System.NullPointerException:参数1不能为null（npe03）

我是用PHP编写的，我的数组是这样的：

$newRecurring = array();
$newRecurring['Name'] = "Recurring: {$recurring['id']}";
$newRecurring['npe03__Amount__c'] = $recurring['amount'];
$newRecurring['npe03__Date_Established__c'] = date('Y-m-d', strtotime($recurring['date']));
$newRecurring['npe03__Installment_Period__c'] = 'Monthly';
$newRecurring['npe03__Organization__c'] = $account; //I double checked, it is a valid Id

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有人能帮我吗？

另一个专门为Salesforce服务的网站Stack Exchange，在那里这个问题可能会得到更多的关注：非常感谢~~