[Koha] Amazon cover images issue

I have enabled Amazon cover issues but it is not always showing images for every book. I have checked to make sure the items where it is not showing have valid ISBN numbers and when I search for the ISBN number on amazon it shows the book with an image. I have disabled Google Jacket and local image storage. I have tried rebuilding the zebra index and rebooted but nothing seems to fix it. I have tried switching ISBNs to other items to see if it is the item and cannot find a pattern for which ones display and which ones do not. Anybody have any suggestions on what to check? -- *Paul Dokken* Information and Digital Technology System Administrator