Found an issue:
Code:
$message .= "INSERT INTO `merchantlist` VALUES ('$merchant_id', '" . $n++ . "', '$item', '-1100', '', '0', '65535', '100');\n";
Should be:
Code:
$message .= "INSERT INTO `merchantlist` VALUES ('$merchant_id', '" . $n++ . "', '$item', '-1100', '0', '0', '65535', '100');\n";