Apart from anything else, that tape has the 'Dangerous era' Epic logo, which came into use in 1991 with Sony Music releases of Epic artists.

The original 1980s releases all had the 'old' logo:
en.wikipedia.org/wiki/File:Epicrecords-logo.png

This logo was revived in 2006, it is the present day logo. Therefore this tape was issued sometime between 1991 and 2006, but most likely prior to 2001 when the Special Edition with bonus tracks was released.

In addition, the song title of "Billie Jean" is mispelled (reads: BillY Jean).

Hi Guys: I noticed those things as well. The odd thing is, could/would Sony possibly release something with a MISSPELLED "Billie Jean"?

Also, Funky1, there is another clue in that the front reads "Sony Music". Apart from a possibly Japanese release, this would not have been used as the label name in the 1980's.

Unfortunately I think this cassette is unofficial. But I think that we should take this occasion to learn that we should be very cautious when we buy Michael's stuff, especially NOW.

I dunno, maybe I'm too stupid, but I'm constantly getting an error when trying to upload new items:

Error: Cannot write to product image directory: /home/mjjcoll/public_html/components/com_virtuemart/shop_image/product/

One got through after several attempts.
Am I doing anything wrong?

Not Agent, you're not stupid at all. It's that sometimes our server makes some mistakes and it could be probably due to this.

You asked if there's a size limit to upload an image and yes it is. If you use a photo editor like Photoshop, Paint etc.. please resize the resolution of your images if they're heavy, leaving the quality intact. We usually add pics of no more than 100-150 kb with a high quality. You can select this useing a resize image tool in your photo editor indeed. If you have troubles in doing this, and you have to add many items, we will try to tell you how to do it, especially with a special software called RIOT which resizes pics in bunches so you won't have to waste too much time in doing so. Please, just try one more time with a lower res and if you aren't able to add an item yet, and it gives you the same error as above, we will tell our webmaster what's going on. Just one thing we would like to ask you: if you have many items to add, please double check if they are not in the site yet, going to search on the main page. In fact, we wish we could have only unique items and not dupes, so this way you can upload items we don't have yet and set those already in aside. :-)