Thank you again for your kind comments. I spent this morning to see what the problem is exactly and found SOAP::WSDL 1.20 was trying to find an appropriate input/output message using /definitions/service/port/@name value while it has to use /definitions/portType/@name value. I've added a line,
$soap->_wsdl_portname('ServiceName'); #retrieved from /definitions/portType/@name
and everything seems working so far. Well now it's so easy to write a code that I can't stop laughing :-)
And thanks for V2 series info. I'm gonna try it when I feel the current version is not powerful enough for what I want to do.
It has been almost 6 weeks since I started lerning Perl by myself and now I feel relieved to find there's so many supportive people around here at perlmonks. I wish I could help another one sooner.