PHP $_SESSION problem

[Drhost]

For some reason my post id session is not carrying over to my grading script page. I grab the post_id from the posts url in my posts page and turn it into a \[code\]$_SESSION\[/code\] to carry it to my grading script page. My \[code\]$_SESSION\[/code\] that holds the logged in users id \[code\]$_SESSION['user_id']\[/code\] if logged in carries over to the grading script but not the post \[code\]$_SESSION\[/code\]. How can I have my posts id carry over to my grading script page?I have \[code\]session_start();\[/code\] at the top of both of my pages.\[code\]$_SESSION['post_id'] = $_GET['pid'];\[/code\]