Try signing out of Amazon, delete the app and reinstall. I has this problem. I am not sure if there are more steps than this but try it and see if it works. There was also another thread earlier on regarding this issue.
Joe, go through the below Android Central thread and then click on the link I offered in my last post and scroll through that thread to find your answer. I wish I could remember exactly what I did, but the answer in the link from another forum I posted at the bottom.