title: Amazon Product Advertising API Signing Issues
body: <p>i am trying to search in amazon product database with the following code posted in amazon webservice sample codes page</p>
  
  <pre><code>AWSECommerceService ecs = new AWSECommerceService();
  
  // Create ItemSearch wrapper
  ItemSearch search = new ItemSearch();
  search.AssociateTag = "ABC";
  search.AWSAccessKeyId = "XYZ";
  
  // Create a request object
  ItemSearchRequest request = new ItemSearchRequest();
  
  // Fill request object with request parameters
  request.ResponseGroup = new string[] { "ItemAttributes" };
  
  // Set SearchIndex and Keywords
  request.SearchIndex = "All";
  request.Keywords = "The Shawshank Redemption";
  
  // Set the request on the search wrapper
  search.Request = new ItemSearchRequest[] { request };
  
  try
  {
      //Send the request and store the response
      //in response
  
      ItemSearchResponse response = ecs.ItemSearch(search);
      gvRes.DataSource = response.Items;
  }
  catch (Exception ex) 
  {
      divContent.InnerText = ex.Message;
  }
  </code></pre>
  
  <p>and getting the following error</p>
  
  <blockquote>
    <p>The request must contain the parameter
    Signature.</p>
  </blockquote>
  
  <p>and amazon documentation is not clear about how to sign the requests.</p>
  
  <p>any idea how to make it work???</p>
  
  <p>thx</p>