magento soap api v2 catalogProductInfo不起作用

当我如下调用api函数时

When i call the api function as follows

<?php $result = $client->catalogProductInfo($session, $id, null, 'sku'); ?>

我收到以下错误.我肯定所有传递的变量都已正确设置，因为其他magento api函数也能正常工作.

I get the following error. I'm positive that all the passed variables are set correctly, as other magento api functions work just fine.

产品不存在 错误:发生内部错误.

Product not exists Error: An Internal Error Has Occurred.

我假设调用语法有问题.我找不到用sku而不是产品ID调用 catalogProductInfo 的正确示例. 文档 http://www.magentocommerce.com/api/soap /catalog/catalogProduct/catalog_product.info.html 告诉我我的电话是正确的.

I'm assuming that it's a fault with the call syntax. I couldn't find a proper example of calling catalogProductInfo with sku instead of product id. The documentation http://www.magentocommerce.com/api/soap/catalog/catalogProduct/catalog_product.info.html suggests to me that my call is correct.

任何关于我在做错事情的想法都将受到高度赞赏.

Any ideas as to what I'm doing wrong are highly appreciated.