Webservice returns null

Hello experts!

I have developed a Portal Service and created a Portal WebService from the Portal Service. If I return a String from my webservice method everything works fine. But I want to return a object with 2 Strings. I defined a Interface and a Class with my attributs and getter/settter methods. In my WebService method I returned a instance of this class. The WSDL was generated correctly. If I want to consume the WebService the return structure was gernerated fine but the values were null!

Thanks for your help!

Johannes