sync_client connect fails - Invalid argument

[Steven Ingram]

I am trying to perform manual (and eventually automatic) replication
with Centos 5.3 package (2.3.7-2.el5_3.2). Following the suggestions
of other posts, I have tested with synctest and imtest. Although both
of these work (they connect and authenticate), sync_client always
yields:

Can not connect to server 'sm1.4test.net', retrying in 15 seconds.

The message logged is "imap1 sync_client[25737]:
connect(sm1.4test.net) failed: Invalid argument".

I've run several commands all with the same result:
/usr/lib/cyrus-imapd/sync_client -v -r,
/usr/lib/cyrus-imapd/sync_client -r, /usr/lib/cyrus-imapd/sync_client
-m user.steve

Looking at the replica (sync_server), no packets make it to that box.

Looking at the error message there should be some argument of
sync_client that is not correct. Here is the sync portion of the
imap.conf:

sync_host: sm1.4test.net
sync_authname: cyrus
sync_password: secret
sync_log: 1

As there aren't that many options for sync_client, I'm not really sure
what's incorrect or missing. Is replication broken in this version?
Everything else seems to work perfectly.

Steve