所以，我解决了。

 $operationNumbersArray = array('1234','1235');

 ...

       'operationNumbers' => array(
           'operationNumber' => $operationNumbersArray
        )

测试和摆弄，我无意中删除了另一个强制性的值。该API未给出警告（忽略）。

During my testing and fiddling about, I had inadvertently removed another value that was mandatory. The API did not give warning of it's omission (sadly).