Error turning me mad... help please

[Deaths]

I've been working on this for a long time, and now this error pops up out of nowhere.

It gives me this error:

Fatal error: Call to a member function on a non-object in /xxx/yyy/public_html/forum/profile.php on line 2606

This is what I've added on line 2606:

PHP Code:

$installs = $DB_SITE->query("
            SELECT hack.threadid, hack.hackid, hack.userid, hack.dateline, hack.version_vb, hack.titre AS title, hack.nb_install, hack.version_hack, hack.description
            FROM " . TABLE_PREFIX . "hacks AS hack
            LEFT JOIN ". TABLE_PREFIX ."hacks_install AS i ON (hack.hackid=i.hackid AND hack.threadid=i.threadid AND hack.userid=i.userid)
            WHERE hack.userid = $userid"); 


I know it'll probably be something like a typo, because I've been working for this 12 hours strait, and havent had any sleep for about 24 hours either :/


Help is appreciated, as always.