A CORBA_UNKNOWN error is an error which was thrown by server side code, but not handled there and not wrapped in an IDL-defined exception so that the client gets some idea of what has happened. You saw it on your client, right?

Often times a CORBA_UNKNOWN exception is a null pointer or similar exception. If you catch it on your client and print its stack trace and post it here I will probably be able to tell you where it is occurring.

If you're more DIY, you could change your server-side code to catch all exceptions or, to be less intrusive, run a debugger against your code and catch Exceptions and Errors as they occur.

Dermot