Didi you solve the problem? I had the same error with a Remote EJB. When i try to lookup the EJB the lookup code throw the same error.
Yes - However in our case remote EJB (business method) was taking longer time and jboss was doing failover which is not expected as it would submit duplicate transactions.
Do you have same issue? If you got error in the ejb lookup itself then you might have some other issue like firewall/network etc.