I just finished follow this tutorial: https://xenforo.com/community/threads/how-to-read-and-write-into-the-database-with-a-page.23560/ because I want to get into making my own add ons. However after completing it, when I test out the add-on I get the error: Security error occurred. Please press back, refresh the page, and try again. What causes this error and how can i fix it? Thanks.