it looks like this code is causing the error:
for ($n=0; $n<sizeof($eCart->Items); $n++) {
$ParamProductID2_WADAsiteezyecproducts = "-1";
if (isset($_GET['ProductID'])) {
$ParamProductID2_WADAsiteezyecproducts = (get_magic_quotes_gpc()) ? $_GET['ProductID'] : addslashes($_GET['ProductID']);
}
$ParamProductID2_WADAsiteezyecproducts = $eCart->Items[$n]->ID;
$ParamProductID2_WADAsiteezyecproducts = "-1";
}
to be honest, i'm not really sure what you are trying to do with that code, but it doesn't look right.
you could probably fix the error by adding a line to define the $ParamProductID2_WADAsiteezyecproducts vartiable before the for loop
$ParamProductID2_WADAsiteezyecproducts = "-1";
for ($n=0; $n<sizeof($eCart->Items); $n++) {
$ParamProductID2_WADAsiteezyecproducts = "-1";