File Upload for product not working

www.fateitalia.it/administrator/index.ph...roduct&task=edit&cid []=1
-- HikaShop version -- : starter 2.2.3
-- Joomla version -- : 3.2.2
-- PHP version -- : 5.5.7
-- Browser(s) name and version -- : Chrome
-- Error-message(debug-mod must be tuned on) -- : no message

I try to upload a file to a product (I'll sell PDFs), but no file found in upload or upload/safe directories.
No way to download the file after the purchase (file not found message)

I can upoload the same files in the media menager.

What's wrong?

EDIT: sorry, it worked. don't know how, but it worked.

Well,

I think it was a mixture of filesize and filename.

Thank you!