oracle901 solaris8

use "publish" tool to publish a corba object:
publish -republish -u SCOTT/TIGER -schema SCOTT -s sess_iiop://netra20:2481:cctest1 /test/HelloCorb server/HelloImpl common.HelloHelper

when errors accure:
javax.naming.CommunicationException: Unknown service: :session1 [Root exception is
javax.naming.CommunicationException: Unknown service: xxx.xxx.xxx.xxx:2481:cctest1]
*** Error code 1

I don't know what's the matter.Maybe some of my configure is wrong.
Is there some specialist can help me resove the problem?
Thanks a lot !