When I add my credential and click "save and test," I get a message that says my credentials are correct and should have no trouble searching. But then when I go to write/edit a post, I get this: "You have not yet set up your Amazon credentials. In order to search for products using the Amazon Reloaded for WordPress plugin, you should do so now."
If the credentials will not store, this plugin is useless. And, 'though the developer's site says that the plugin is supported, it says to leave questions "in the comments" and there is apparently no comment section available.