In the source code for the page, I can see that the item id does not appear to be coming from the database:
for item 1:
<input type="hidden" name="eCartFinal_1_ID_Add" value="0" >
for Item 2:
<input type="hidden" name="eCartFinal_2_ID_Add" value="0" >
I'll need to look at the php code on the page to determine what is wrong.
Please compress the "Store.php" file into a zip archive. When replying, scroll do the reply to topic page and click the manage attachments button. there will be a place for you to upload you zip file and attach it to your reply.