API Credentails not Working

I have my correct username, access key and secret access all entered correctly from the Product API section on Amazon Affiliates. I've tried creating multiple different keys and the post will not work. I red X just appears after I click run this action. In the logging this error appears: Exception thrown -> <br/>The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.! If need to troubleshoot I can send log in information. Thanks!