log on using connect string hangs

The server has two oracle homes on it a 10.2.0.3 and a 11.2.0.1. I'm using the listener on the 11g side and the database is 10.2.0.3, I'm using port 1528 just so we can differentiate between old and new dbs. I've done the same thing on other servers and never had a problem until now.  There is only one listener.
I can connect to the database if I set the oracle_sid, no problem. But when I try to use the connect string (i.e. sqlplus scott/tiger@test), the connection just hangs for as long as I can wait until I do a control-c.