ok, i've had a quick look through.
I noticed a few things on your items_Detail.php which don't seem right.
$Safety->GetContent(); is declared twice, lines 8 and 11
the // WA eCart Redirect is declared twice, around lines 131 and 137
starting from around line 345, you have forms for rainbow_1_ATC_, Safety_2_ATC_ and Safety_1_ATC_
after changing a bit of code to make it work with my connections and recordsets, i tried placing an add to cart button on items_detail2, and it seems to work ok.
hope this helps