the photos of ads not appear in admin panel if we didn't "Keep original image", so I prefer to use the thumbnail in code, place original.
the solve: in file oc-admin/themes/modern/items/frm.php line 165 :
_original. >>> _thumbnail.
and the same for user edit items: in file oc-includes/osclass/frm/item.form.class.php line 380:
_original. >>> _thumbnail.
and one more bug
if we delete photos from user panel, photos will deleted from the server.
BUT if we delete them from admin panel they stay on the server. (I coudn't solve this one yet
)