Getting org.omg.CORBA.BAD_PARAM exception

Hello,

I am trying to connect to CORBA service with simple client and I am
getting

org.omg.CORBA.BAD_PARAM:   vmcid: 0x0  minor code: 0  completed: No
       at
com.pikeelectronic.calc.CORBAClient.CalculatorHelper.narrow(CalculatorHelper.java:
60)
       at com.pikeelectronic.calc.CORBAClient.Client.main(Client.java:
23)

I am using JacORB on both client and server side. I use
corbaloc::localhost:40000/MyService. I googled that I need to run
Naming Service but it did not help (I have tried the naming service
from the JacORB distribution).

Thanks for help

Lukas