Issue: Review Problem

Hello, my issue are quite a weird one. I was trying to get some point and found a thread that asking us to make a preview and we will get the point. I click the given link n try to preview but the web said need to be log in before i can preview. But at that time, i already log in to AF web. But i did try to log in but they said that i havent register. That is even weird because i am browsing AF forum while trying to log in. Please help me!!