Alexa API: Not working - amazon-web-services

Question

Documentation here:
http://docs.amazonwebservices.com/AlexaWebInfoService/latest/
http://awis.amazonaws.com/?
Action=UrlInfo
&AWSAccessKeyId=[Your AWS Access Key ID]
&Signature=[signature calculated from request]
&SignatureMethod=[HmacSha1 or HmacSha256]
&SignatureVersion=2
&Timestamp=[timestamp used in signature]
&Url=[Valid URL]
&ResponseGroup=[Valid Response Group]
I don't understand this...
&Signature=[signature calculated from request]
&SignatureMethod=[HmacSha1 or HmacSha256]
How do you calculate the signature?
&AWSAccessKeyId=[Your AWS Access Key ID]
This does not work as well! There's no AWS secret key required here here, but it simple doesn't recognize the Access Key ID, in my account.
AWS was not able to authenticate the request: access credentials are missing
I can't do something as simple as:
http://awis.amazonaws.com/?Action=UrlInfo&AWSAccessKeyId=AKIAISCXZCPDLPUDDAVA&SignatureVersion=2&Url=http://www.google.com&ResponseGroup=TrafficData

Answer 1

Have you checked following things, its given in Documentation Under Authentication Errors Section:
If you get an authentication error then one of the following is probably true:
You are not signed up for the Alexa Web Information service. Even if you already have an Amazon Web Services account, you must separately sign up for the Alexa Web Information service at Amazon AWS.
Your credit card is invalid or expired.
You have not URL encoded your Timestamp and Signature values.
If you are seeing intermittent authorization errors, this is the most
likely problem. You should not see any "+" signs in your Signature, for example.
You are not generating the Signature correctly. Please see the code samples.
The clock on the computer making the requests is not set correctly.