Hi!
I’m getting a similar issue on wordpress 3.5.2, are you using this version? If so, then I will look into it and send you a fixed version, but first please use the “Open Support Ticket” on the right top side of the screen so you verify your product and open another topic. (you can copy this text there, what you just wrote) Then I will be able to upload files, that are only visible for you. (I dont want guests to download the product for free)
I will look into this first thing tomorrow.