Oracle 11g Database not registering with listener

I have two instances of an Oracle database installed on a Unix zone. Unfortunately, one of them won't register with the listener when it starts.

In the $ORACLE_HOME/dbs folder I found a file called inittstep.ora, which was the init file for the working database. In it, I found:  *.local_listener='LISTENER.tst.tadnet.net'
In the file for the non-working database, I found a similar entry but it was different so I changed it to contain the value found in the good file; however, this still didn't help.

I started the database and tried this:

SQL> show parameter local_listener

alter system set LOCAL_LISTENER='LISTENER.tst.tadnet.net' scope=both

and it worked.

See:
http://edstevensdba.wordpress.com/2011/07/30/exploring-the-local_listener-parameter/