MUC on multi domain servers

Hi all. I am now investigation openfire to use for our project. We have couple of companies, each company has it’s domain and openfire server. I have tested locally to send messages between users from different domains and it works good. We want to make group chat rooms for cross domain users. I created a room on the server on domain1.com and try to invite user from domain2.com, but - no result. User from domain2.com doesn’t receive any messages.

How is it possible to make group chat for users from different domains?