Thanks gellyfish, but I'm still having some problems. Here's how call() is used in the SOAP::Lite docs:

# you should specify uri()
my $soap = SOAP::Lite
  -> uri('http://my.own.site/CLASS') # <<< CLASS goes here
  # ..... other parameters
;
my $obj = $soap->call(new => @parameters)->result;
print $soap->call(method => $obj)->result;
# $obj object will be updated here if necessary, 
# as if you call $obj->method() and method() updates $obj
# Update of modified object MAY not work if server on another side 
# is not SOAP::Lite
[download]

And here's what I've done:

#! /usr/bin/perl -w
use strict;
use SOAP::Lite;

my $soap = SOAP::Lite
  -> proxy( 'http://dg.homeunix.org/cgi-bin/soapserver.cgi' )
  -> uri( 'http://dg.homeunix.org/Greeter' )
  -> on_fault( sub { my($soap, $res) = @_;
         die ref $res ? $res->faultstring : $soap->transport->status, 
+"\n";
});

my $greeter = $soap->call( new => 'Doug' )->result;
print $soap->call( formal => $greeter )->result;

__END__
[download]

...and I get the same error as before.