Need help with PHP flat file login system.

I am trying to create a flat file login system, when I log in to the system via the username and password I set in my .txt flat file, I recieve an error message that reads:

"Warning: file(/LoginTest/userlist.txt) [function.file]: failed to open stream: No such file or directory in /home2/shb8_008/bt3software.com/public_html/LoginTest/validate.php on line 12
Could not open file /LoginTest/userlist.txt"

The code for the validate file around line 12 is:

"require_once('config.php');

function checkLogin($user,$pass)
{
      global $file;      
      $users=file($file) or die("Could not open file <b>$file</b>");
      foreach($users as $userInfo)
      {
            if ( trim(substr($userInfo,33))==$user && substr($userInfo,0,32)==$pass )
                  return 1;
      }
      return 0;
}"

I am new to PHP and would appreciate any help you guys gave provide.  Thanks a lot.  

-Jon