When accessing a WSDL based Service, SOAP::Schema seems to parse the Service's parameters into a list ref containing just an empty string.
This behaviour causes https://sourceforge.net/tracker/?func=add&group_id=66000&atid=513017 , and thus causes SOAP::Schema calls to fail.
https://sourceforge.net/tracker/?func=add&group_id=66000&atid=513017
can be (and will soon be) fixed by checking whether each element is a reference, but that's just a workaround.