Estou tentando colocar um blob com a API de descanso do Azure. Fiz uma solicitação "GET" com êxito, mas tive problemas com a solicitação "PUT". Quando tento fazer a solicitação "PUT", obtenho um erro 404 (vi a mesma postagem no stackoverflow, mas ele não me ajudou). Alguma sugestão?

public void UploadBlobWithRestAPI(string uri,  DateTime now)
{
    string blobName = "test.txt";
    string method = "PUT";
    string sampleContent = "This is sample text.";
    int contentLength = Encoding.UTF8.GetByteCount(sampleContent);
    string queryString = (new Uri(uri)).Query;
    string blobContainerUri = uri.Substring(0, uri.Length - queryString.Length);
    string requestUri = string.Format(CultureInfo.InvariantCulture, "{0}/{1}{2}", blobContainerUri, blobName, queryString);
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(requestUri);
    string nnow = now.ToString("R", System.Globalization.CultureInfo.InvariantCulture);

    request.Method = method;
    request.Headers.Add("x-ms-version", "2015-02-21");
    request.Headers.Add("x-ms-date", nnow);
    request.ContentType = "text/plain; charset=UTF-8";
    request.Headers.Add("x-ms-blob-type", "BlockBlob");
    request.ContentLength = contentLength;

    using (Stream requestStream = request.GetRequestStream())
    {
        requestStream.Write(Encoding.UTF8.GetBytes(sampleContent), 0, contentLength);
    }

    request.Headers.Add("Authorization", AuthorizationHeader(method, now, request, "", ""));

    using (HttpWebResponse resp = (HttpWebResponse)request.GetResponse())
    {
        MessageBox.Show(resp.StatusCode.ToString());
    }
}


public string AuthorizationHeader(string method, DateTime now, HttpWebRequest request,
        string ifMatch = "", string md5 = "")
{
    string MessageSignature;
    string StorageKey = "xxx";
    string StorageAccount = "upgradedevstorage";

    MessageSignature = String.Format("{0}\n\n\n{1}\n{5}\n\n\n\n{2}\n\n\n\n{3}{4}",
        method,
        (method == "GET" || method == "HEAD") ? String.Empty : request.ContentLength.ToString(),
        ifMatch,
        GetCanonicalizedHeaders(request),
        GetCanonicalizedResource(request.RequestUri, StorageAccount),
        md5
        );

 ???   //string MessageSignaturePut= String.Format("{0}\n\n{1}\n\n{2}{3}",
    //    method,
    //    "text/plain; charset=UTF-8",
    //    GetCanonicalizedHeaders(request),
    //    GetCanonicalizedResource(request.RequestUri, StorageAccount)
    //    );

    byte[] SignatureBytes = System.Text.Encoding.UTF8.GetBytes(MessageSignature);

    System.Security.Cryptography.HMACSHA256 SHA256 =
        new System.Security.Cryptography.HMACSHA256(Convert.FromBase64String(StorageKey));

    string signature = Convert.ToBase64String(SHA256.ComputeHash(SignatureBytes));

    string AuthorizationHeader = "SharedKey " + StorageAccount
        + ":" + Convert.ToBase64String(SHA256.ComputeHash(SignatureBytes));

    return AuthorizationHeader;
}