(LinkedIn) User Agreement

8.2. Don'ts. You agree that you will not:

• …Use manual or automated software, devices, scripts robots, other means or processes to access, “scrape,” “crawl” or “spider” the Services or any related data or information;…

I am guessing your actual problem lies with JavaScript stuff regarding their sessions in which case you would need a JS aware agent like WWW::Mechanize::Firefox or WWW::Selenium but it could be as simple as changing the name of the UserAgent so it’s not a flagged bot/agent name. Still you’re not supposed to do this here and I personally wouldn’t help you because it can cast Perl and its fans in a bad light and as poor Netizens.