iTunes Artwork Screensaver

I'm having problems with the itunes artwork screensaver.
I let itunes try to find most of the album art on it's own, but there were a few that it couldn't find. I did the drag-and-drop off the internet for the few it couldn't find, but that screensaver will only show me those 4 or 5 album covers that I added. It won't include any that itunes found. Does anyone know how to fix this?
Thanks guys.

i use the amazon album art widget, highlight the songs in itunes i want to find album art for then click the arrow, it will find the correct album art then you can apply it and it will do it all for you. i use the itunes album artwork screensaver and never had a problem with it by doing it this way.

maybe some album art for saved in a different folder for you? i am not sure