Error 4457- establishing session to Domino Server from servlet in AIX

[rosav]

Hello,
My environment is as follows:
Machine A: Windows 2000, Domino Server 5.07
Machine B: AIX 5.1, WebSphere 4.0.5.
A servlet is running in WebSphere (machine B). I have an EAR that contains this servlet. It tries to establish a remote (IIOP) session to machine A. EAR also contains NCSOW.jar.
I get the following error:
Could not get IOR from HTTPServer Id=4457.

Important things to take into account:
- NCSOW.jar contained in my EAR is the one I have got when I installed Domino Designer in Windows. Can this be a problem ?? (because EAR is executed in AIX).
- If I substitute AIX machine by a Windows 2000 machine with WebSphere 5, I establish successfully the session.
- In AIX, I have tried to use NCSO.jar instead of NCSOW.jar, but then it is not possible to install the EAR. I get the following error:
Servlet Error: Class org/omg/CORBA/Object violates loader constraints: definition mismatch between parent
and child loaders: java.lang.LinkageError: Class org/omg/CORBA/Object violates loader constraints: definition
mismatch between parent and child loaders at lotus.domino.cso.Session.OREFtoSession

Please, I need help. Thanks a lot.
Rosa V.