使用PHP客户端的WCF服务 - 复杂类型作为参数不起作用

I have a WCF service with three methods. Two of the methods return custom types (these work as expected), and the third method takes a custom type as a parameter and returns a boolean. When calling the third method via a PHP soap client it returns an 'Object reference not set to an instance of an object' exception.I have a WCF service with three methods. Two of