Error when I run game add script for v3 arcade

[chilllax]

Whenever I try to run the script to add a game in the v3arcade it gives me this error message
Fatal error: Call to a member function on a non-object in /home/chilllax/public_html/admincp/curveball.game.php on line 31

and on line 31 it says this

PHP Code:

$gameexists = $DB_site->query("SELECT * FROM " . TABLE_PREFIX . "games WHERE shortname='curveball'"); 


Thanks for the help

im sure this is a really easy problem to fix for all of the people here that have the coding knowledge that I only wish I had, please help