Amazon itemsearch gives me error 400 ! why that happened

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C#

ASP.NET

Amazon

API

app.config

program.cs

    static void Main(string[] args)
    {
        // Instantiate Amazon ProductAdvertisingAPI client
        AWSECommerceServicePortTypeClient amazonClient = new AWSECommerceServicePortTypeClient();

        // prepare an ItemSearch request
        ItemSearchRequest request = new ItemSearchRequest();
        request.SearchIndex = "Books";
        request.Title = "WCF";
        request.ResponseGroup = new string[] { "Small" };

        ItemSearch itemSearch = new ItemSearch();
        itemSearch.Request = new ItemSearchRequest[] { request };
        itemSearch.AWSAccessKeyId = ConfigurationManager.AppSettings["accessKeyId"];
        itemSearch.AWSAccessKeyId = ConfigurationManager.AppSettings["secretKey"];
        itemSearch.AssociateTag = "my value";

        // send the ItemSearch request
        ItemSearchResponse response = amazonClient.ItemSearch(itemSearch);

        // write out the results from the ItemSearch request
        foreach (var item in response.Items[0].Item)
        {
            Console.WriteLine(item.ItemAttributes.Title);
        }
        Console.WriteLine("done...enter any key to continue>");
        Console.ReadLine();

    }
}

What I have tried:

I tried to sign it but with no hope

signingBehavior which in the app.config build succeded bud has blue line under it said invalid child element signingBehavior , is that the problem but the build succeeded I don't know any one have any idea