I have exactly the same problem.

The thing is that SOAP::Lite uses the wrong namespace in the envelope here.

The funny thing is that if you do this:

my $soap = SOAP::Lite->service("http://www.webservicex.net/globalweath
+er.asmx?WSDL");

print Dumper($soap->serializer->{_namespaces});
[download]

you can see that the proper namespace is actually registered but it later seems to get overwritten in the serializer...
Explicitely calling register_ns does not change a thing, so I really think it is a bug.

I finally got it working (without WSDL alas) like this:

use strict;

use SOAP::Lite +trace => "debug";

my $address = 'http://www.webservicex.net/globalweather.asmx';
my $action = "http://www.webserviceX.NET/GetCitiesByCountry";
my $namespace = 'http://www.webserviceX.NET';
my $call = "GetCitiesByCountry";

my $soap = SOAP::Lite
    ->uri($namespace)
    ->on_action(sub { $action } )
    ->proxy($address);

my $arg = SOAP::Data->name(CountryName => "Singapore");

$soap->call($call => $arg);
[download]

Quite a lot of work for such a simple thing - is this because .NET is quirky or is it that SOAP::Lite (I have 0.710.10) has problems with WSDL (or am I simply being stupid?).