new parcel product: product list popup shows add product page

basically that's the bug: when i try to add a new parcel product node and i click on "list products" i get a popup, but instead of product list it's filled with add product main page (the page where u select the kind of product to add).

i'm digging to find the bug, but i'm not experienced in drupal framework...basically i have no clue about where to start to search...