[Plugin: VoucherPress] Voucher will not download after upgrade

I just upgraded to the latest version of VoucherPress. I have two previous vouchers in my database that still seem to work fine. Now when I create a new voucher and try to download it, I get: File Not Found. I have the box checked to make the voucher live.

Does anybody know what could be going on? This is a great feature for my client and I would hate to delete the plug-in.