Millisecond Forums

I am trying to implement an experiment in which I have 16 different page of stimuli. I want the pages to be presented to each subject in a randomly selected order and for each page to only show up once. This is what I've written into my script but whenever I run the script it keeps re-using pages, meaning not all of them get shown and some get shown more than once. Can someone help me understand what I've done wrong here?