change line 18:
$WADbSearch1->keywordComparison($KeyArr1,"".$_GET['prodName'] ."","AND","Includes",",%20","%20","%22","%22",0);
to:
$WADbSearch1->keywordComparison($KeyArr1,"".((isset($_GET['prodName'])?$_GET['prodName']:"")) ."","AND","Includes",",%20","%20","%22","%22",0);