error 'cx_ai_system_fault'

Hi,

I have tried to call a web service method and encountered this.

The rough process is as followed:

1, Creating an RFC and publishing it as web service

2, Go to SOAMANGER, some configuration in Single Service Admininstration and get a WSDL

3, Using the WSDL to generate a proxy class

4, Create an object of the class and call the method in my report

I have been searching Google and one thing I didn't do is to set logical port and I debug my CREATE OBJECT and found the parameter

logical port name of constructor is null. Is it the reason that caused a  'cx_ai_system_fault' error?