I made a very similar extension last week (https://chrome.google.com/webstore/detail/always-smile/fpaapignoneonaghhkoddkghglbppdmg https://chrome.google.com/web

I made a very similar extension last week (https://chrome.google.com/webstore/detail/always-smile/fpaapignoneonaghhkoddkghglbppdmg https://chrome.google.com/webstore/detail/always-smile/fpaap...) and encountered this issue, too. You can resolve it by going to http://smile.amazon.com http://smile.amazon.com and choosing your charity. After that, the extension should work as expected.