Web services are considered a new paradigm for building software applications that has many advantages over the previous paradigms. Web service testing is a very important factor to increase or decrease the requester's trust of a given Web service. However, Web service testing still facing many problems; one of these problems is that the platform where a Web service is deployed may affect the testing results; this research proves this claim by demonstrating how the robustness and security quality attribute of a Web service may be affected by the platform this Web service is deployed on. This will be accomplished by comparing the responses of Web services accomplishing the same task deployed on different platforms, namely, axis, GLUE and Microsoft .NET. This study approach proves that Web services robustness and security testing do actually depend on the platform.