Restrict Access on eCart Display Page

I am not sure if what I am trying to do is even possible, but I would like to set some show if conditions on my cart display page. I made a rule to exclude a certain description when eCart object conditions are met. However, when I upload and test my page, I get the following error.

Fatal error: Call to a member function DisplayInfo() on a non-object in /home7/commonsc/public_html/WA_SecurityAssist/HelperGroupsRulesPHP.php on line 8

The following includes line 8 in the code.
<?php

function WA_Auth_GetComparisonsForRule($ruleName){
$comparisons = array();

switch ($ruleName){
case "Candle":
$comparisons[0] = array(TRUE, "".$CommonScentsCart->DisplayInfo("Itemtype") ."", 1, "CD");
break;
case "Manual":
$comparisons[0] = array(TRUE, "".$CommonScentsCart->DisplayInfo("Price") ."", 5, "140");
break;
}
return $comparisons;
}


function WA_Auth_GetGroup($groupName){
$group = Array();

switch($groupName){

}

return $group;
}

?>

Thanks in advance.

Kevin