Problem with SMF (sourcedir)

[Timhortons]

Notice: Undefined variable: sourcedir in /home/timhortn/public_html/forum/index.php on line 49

Warning: require_once(/QueryString.php) [function.require-once]: failed to open stream: No such file or directory in /home/timhortn/public_html/forum/index.php on line 49

Fatal error: require_once() [function.require]: Failed opening required '/QueryString.php' (include_path='.:/x10hosting/php2/lib/php') in /home/timhortn/public_html/forum/index.php on line 49

I keep getting this when I try to go on my forum.

 

[Corey]

This is an error with your script. Like it says "sourcedir" is undefined, you'll have to define it