Cannot get download button to show up on purchases

If it's not one thing, it's another LOL
I cannot get my downloads to work, no matter what I do. As far as I can see I have everything set up correctly yet a purchased product yields no download link at all. Worst part - it used to work before I upgraded the cart :/
My entire site contains downloadable content only (if that makes a difference).

In my attributes, I have Option Name: Download (Radio button) and Option Value: Zip File.
All zipped files are in the download folder and are appearing with a green icon.
I have Expiry Days set to 0 and Maximum download set to 10.
Used for display purposes only: No.
Attribute free when product is free: Yes.
Default attribute to be marked selected: Yes.
Apply discounts used by product special/sale: Yes.
Include in base price when priced by attributes: Yes.
Attribute required for text: No.
Paypal order status is set to Delivered [3].
The Add To Cart Box on tpl_product_info_display.php is unchanged.

I don't know where else to look. Can anyone help me please?

What are your settings in Configuration->Attribute Settings for the first 8 download-related settings.

The purchase yields no download link, but do you get the notice that "Downloads are not available until payment is confirmed"?

Are there any debug-log files present in your /logs directory (for v1.5.1+) or /cache directory (for earlier versions)?

Enable Downloads true
Download by Redirect true
Download by streaming false
Download Expiration (Number of Days) 0
Number of Downloads Allowed - Per Product 20
Downloads Controller Update Status Value 4
Downloads Controller Order Status Value >= lower value 2
Downloads Controller Order Status Value <= upper value 4
Enable Price Factor true

No notice of any kind. Payment is marked as delivered on invoice and on account page.

There's a couple of old parse error logs (which are no longer relevant), and the following ...
[16-Mar-2014 06:04:08 America/Chicago] PHP Warning: filesize() [<a href='function.filesize'>function.filesize</a>]: stat failed for /home/shopwick/public_html/wicked21/download/Z-XmasPT.zip in /home/shopwick/public_html/wicked21/includes/templates/template_default/templates/tpl_modules_downloads.php on line 41

I don't have an override in Wicked21 (name of template) and the default file hasn't been changed in any way.
EDIT The reason for that error is that file does not exist anymore.