bekomme folgende meldung in der Test-Klickdatei

Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in /var/www/web361/html/klammunity/content/verdienen/vcheck.php on line 55

wäre folgende zeile

$usr = mysql_fetch_assoc (db_query ('SELECT max_forced, art, sort FROM '.$db_prefix.'_userdaten WHERE uid = '.$_SESSION['uid'].' LIMIT 1'));