Http 500 Internal Server Error with Amazon Product Advertising API

I am trying the Amazon Product Advertising API, following their tutorial here.

Before doing any coding, I am attempting to follow the tutorial and use the Signed Requests Helper form online to prove the concept. I enter in my Access Key ID开发者_JS百科 and Secret Access Key, and then enter in the following in the Unsigned URL box:

_http://ecs.amazonaws.com/onca/xml?Service=AWSECommerceService
&Version=2010-11-01
&Operation=ItemSearch
&SearchIndex=Books
&Keywords=harry+potter

I copy and paste the contents of Signed URL box into my browser's address bar (with correct access key and signature):

_http://ecs.amazonaws.com/onca/xml?AWSAccessKeyId=[MY_ACCESS_KEY]&Keywords=harry%20potter&Operation=ItemSearch%0D&SearchIndex=Books%0D&Service=AWSECommerceService%0D&Timestamp=2011-05-30T07%3A56%3A17.000Z&Version=2010-11-01%0D&Signature=[MY_SIGNATURE]

In return I get a HTTP 500 Internal Server Error.

(Note I have inserted the unscore before both example hyperlinks as stackoverflow won't allow more than 2 hyperlinks for newbies.)

I've tried IE8, and Chrome, and have also tried the .co.uk domain as I reside in the UK. I have also looked at the AWS forum with no luck. Any help would be appreciated...

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I have tried generating Signed URL with the page you linked to using my Access Key ID and Secret Access Key and I do get the correct response.

One thing I noticed is that your signed URL contains an extra character (%0D - newline character?) ending some of your request parameters values. Were these characters been added when you copied the sample URL in the unsigned URL input? Please try fixing the unsigned URL until these characters do not show up in the signed URL box, then try that signed URL again.