There are a few reason why album artwork does not display as intended.
1. MP3 TAGS - Even if your tags are incorrect, in most cases, as long as your music is somewhat popular and is listed in the last.fm database, you should see at least 2 out of 10 of the album artwork display. If the mp3 tags (artist, album and track title) are missing, or spelt incorrectly, they system will not find the image.
2. API Key - If your using your own key, you will still need to enter our domain name (http://shoutjockey.com) when you create your key on the last.fm site. If you use a key for a different domain, the images will not appear.