问.net获取SDK获取临时密钥时 报错？

            string bucket = "myblog-13235761478";  // 您的 bucket
            string region = "ap-guangzhou";  // bucket 所在区域
            string allowPrefix = "exampleobject"; // 这里改成允许的路径前缀，可以根据自己网站的用户登录态判断允许上传的具体路径，例子： a.jpg 或者 a/* 或者 * (使用通配符*存在重大安全风险, 请谨慎评估使用)
            string[] allowActions = new str3ing[] {  // 允许的操作范围，这里以上传操作为例
                "name/cos:PutObject",
                "name/cos:PostObject",
                "name/cos:InitiateMultipartUpload",
                "name/cos:ListMultipartUploads",
                "name/cos:ListParts",
                "name/cos:UploadPart",
                "name/cos:CompleteMultipartUpload"
            };
            string secretId = Environment.GetEnvironmentVariable("AKIDOXPCj1lsgFf3GSD6IMC1bvq6v8B"); // 云 API 密钥 Id
            string secretKey = Environment.GetEnvironmentVariable("xkTyIL7A0e3FD241SAFacQxENWO0LVP4"); // 云 API 密钥 Key

            Dictionary<string, object> values = new Dictionary<string, object>();
            values.Add("bucket", bucket);
            values.Add("region", region);
            values.Add("allowPrefix", allowPrefix);
            values.Add("allowActions", allowActions);
            values.Add("durationSeconds", 1800);
            values.Add("secretId", secretId);
            values.Add("secretKey", secretKey);
            values.Add("Domain", "sts.tencentcloudapi.com");

            Dictionary<string, object> credential = STSClient.genCredential(values);
            foreach (KeyValuePair<string, object> kvp in credential)
            {
                Console.WriteLine("{0} = {1}", kvp.Key, kvp.Value);
            }