One point to watch is that because SID is passed via a URL it is likely returned to you as a redirect.

This is where it gets a little tricky. If the LWP::UserAgent->request method it receives a REDIRECT response it calls LWP::UserAgent->redirect_ok which returns FALSE for a POST request and true for all others. If LWP::UserAgent->request() thinks it is a POST request it will never go back(redirect) and get your target page.

I have found the wget tool (found on most Linux distro's) to be very helpful in figuring out these kind of problems

mitd-Made in the Dark
'My favourite colour appears to be grey.'