Networking :: Ddclient Fails With Uninitialized Value When Cache File Exists?

When I run ddclient with an existing ddclient.cache file I get errors saying "uninitialized value" and the remote IP address does not get updated. This pretty much renders ddclient useless. If I delete the cache file then things work fine and the IP address *does* get updated (if need be). I happen to be running version 3.7.3 of ddclient but I've tried this with ddclient 3.8.0 and the result is exactly the same except that the line number in the error changes to line 2030.

Here's the code at that line number :

Code:
if ($config{$host}{'login'} eq '') {
warning("null login name specified for host %s.", $host);
I'm running ubuntu ( 9.04 I think ) and using zoneedit.com for dynamic dns.
Here's a transcript showing the problem.
root@ruby:/var/cache/ddclient# ddclient

[Code]...