in reply to
form not being filled out by WWW::Mechanize
Bear in mind that $m->success only tells you that the response was HTTP 202 OK, not that the content of the returned screen was what you anticipated it should be! All that this tells you is that the server responded with a new page. You have to now check the content of the HTTP data-stream that was returned, to determine what to do next.
The host undoubtedly did send you back some sort of a page ... it’s up to you to figure out whether that page indicates a successful login or not.