Hmm, if that's all your getting then it could be dying at any point, but it looks like definitely early in the script if it's not even giving php errors. If you're familiar with php at all you could try adding some debugging code into ubbt.inc.php, somewhere early in the file, like:
echo "We made it this far";
exit;
and then see if you see it, then keep moving it down until you no longer see that and we might be able to pinpoint what's going on. Otherwise we'll probably need to do a support ticket as I'd need to get FTP information from you to do the debugging and see what's going on.
