Since the content you've gotten from
LWP::Simple is a "Login Required" message, you either did not retrieve the right url or you need to authenticate (login in first to get session/cookie??) in some way or another.
WWW::Mechanize (which uses LWP) can be a very easy way to do this .. Basically your goal is to mimic the steps you would take with IE or Firefox, so keep in mind anything you do there you have to have perl do too..