Not sure exactly what you're doing in the code but i guess you're simply retrieving the initial page and trying to do likewise for the list of friends. more than likely you'll need to send a POST request for these links, with appropriate parameters. the parameters can be sent separately or in the url of a POST request. In any case, to be sure, record a few click-through sessions with something like Ethereal running...to see what is exactly sent and received. looking at browser alone doesn't tell full story.
btw...how are you going to handle the condition of "your friend's friend has you as their friend"..and similar conditions? if not careful, you can make endless loops there, or get wrong answers to questions. in fact, a relational database (structure) may not handle this very well at all...so a hierarchial DB (structure) could be better.
good luck