接口删除资源提示401未授权

public static  bool DeleteImgToQiniu(string url)

        {

            bool result = false;

            Qiniu.Conf.Config.ACCESS_KEY = ACCESSKEY;

            Qiniu.Conf.Config.SECRET_KEY = SECRETKEY;

            CollectHelper collecthelper = new CollectHelper();

            string httpRespOnse= "";

            string httpParams= Base64URLSafe.Encode(url.Replace("http://7xromb.com1.z0.glb.clouddn.com/",""));

            string httpUrl = "http://rs.qiniu.com/delete/" + httpParams;

            string signingStr = "/delete/" + httpParams;

            string sign = HmacSha1Sign(signingStr, SECRETKEY);

            string encodeBase64 = Base64URLSafe.Encode(sign);

            string accessToken = string.Format("Authorization: QBox {0}:{1}", ACCESSKEY, encodeBase64);

            httpRespOnse= collecthelper.CollectHtml(httpUrl, httpParams, CollectHelper.Method.POST, CollectHelper.HtmlEncoding.GBK, CollectHelper.HtmlEncoding.UTF8, accessToken);

            if (httpRespOnse== "") {

                result = true;

            }

            return result;

        }



        public static string HmacSha1Sign(string text, string key)

        {

            Encoding encode = Encoding.GetEncoding("GBK");

            byte[] byteData = encode.GetBytes(text);

            byte[] byteKey = encode.GetBytes(key);

            HMACSHA1 hmac = new HMACSHA1(byteKey);          

            CryptoStream cs = new CryptoStream(Stream.Null, hmac, CryptoStreamMode.Write);

            cs.Write(byteData, 0, byteData.Length);

            cs.Close();

            return Convert.ToBase64String(hmac.Hash);

        }

collecthelper.CollectHtml(string strHeader)

 request.Headers.Add(strHeader)