im trying to debug a problem with my code, i have a main index.php page that shows a list of chapters and when clicked i am brought into another directory /chapters/chapter1/index.php. I am using a template system and im loading the template fine, i have it seperated into an intro container that gives basic information and a button to start lesson which should bring me to a split container that is a split in half page with information to the left and information to the right that isnt implemeneted yet. However when i click the start lesson button my code is returning a null value instead of the chapterid that should be properly linked and im unsure how to fix the problem

i have tryed switching between different keys in sql and amending the files with chatgpt as a guide with no success