listen_addresses = '*' ok, specific address(es) no

I'm running PostgreSQL 8.1.3.  In my postgresql.conf, the following  
works:   listen_addresses = '*'

but the following does not:   listen_addresses = '192.168.1.33'

I get an error:   WARNING:  could not create listen socket for "192.168.1.33"   FATAL:  could not create any TCP/IP
sockets

I'm running Mac OS X 10.4.6 on PPC, if that makes a difference.

For now, listen_addresses = '*' works for me, but I was curious why I  
couldn't use the more restrictive listen_addresses.

Geoffrey
--
Geoffrey S. Knauth | http://knauth.org/gsk