After purchase attachment not always available on product page

My setup is that I create a product for each different file format I want to sell and then combine them into 1 Product Display so that you have a dropdown box under the product where you can choose which file format you want to purchase of the product. After a successful purchase the file is available under the product as displayed in the attached image "availableattachment.png" .

But when I select a different format as in attached image "selectfileformat.png", and I then go and select the format that I purchased, the download attachment is not displayed anymore... And the attachment will only show if it is the same format as what the default fileformat is that is being displayed. If I purchased another fileformat that is NOT as in the image .ART, and I go to the product page and then select the fileformat I purchased, the file isn't displayed.

I hope this explanation makes sense?
Thank you