Few tips:
- How are you using sessions? If by sessionid (ie. not in a cookie) you probably need to add a hidden field with its value to your form so it gets passed to the next page, otherwise you are creating a fresh session where ['ID'] wouldn't be assigned.
- What is this line for as someone above asked: $_GET['mn'];
- Why have this a second time in your IF when it's already included above? require_once('../mysql_connect.php');
- Use $_POST['bill_fname'] instead of $bill_fname for more security andbetter compatibility if your code is used on a server with register_globals off.
- A personal recommendation is use AdoDB database abstraction layer to make cleaner more portable apps and also you can do simple stuff to help you debug like, $db->debug = true; etc...
