Adwords API中的Issu，无法刷新访问令牌 - ＆＃34;错误＆＃34; ：＆＃34; invalid_grant＆＃34;

Question

我正在编写一个代码来使用c＃中的adwords api来获取搜索量，但是它会在行上显示错误＆＃34; page = targetingIdeaService.get（selector）;＆＃34;，下面是我的代码，I在网上找到了这个代码示例。

        AdWordsAppConfig config = new AdWordsAppConfig();
        config.OAuth2ClientId = "MY_OAUTH2ClientID Here";
        config.OAuth2ClientSecret = "MY_OAUTH2ClientSecret Here";


        AdWordsUser user = new AdWordsUser(config);
        AdWordsUser user1=new AdWordsUser()

        using (TargetingIdeaService targetingIdeaService = (TargetingIdeaService)user.GetService(AdWordsService.v201710.TargetingIdeaService))
        {

            TargetingIdeaSelector selector = new TargetingIdeaSelector();
            selector.requestType = RequestType.STATS;
            selector.ideaType = IdeaType.KEYWORD;
            selector.requestedAttributeTypes = new AttributeType[] {
                  AttributeType.KEYWORD_TEXT,
                  AttributeType.SEARCH_VOLUME,
                  AttributeType.AVERAGE_CPC,
                  AttributeType.COMPETITION,
                  AttributeType.TARGETED_MONTHLY_SEARCHES
                };
            List<SearchParameter> searchParameters = new List<SearchParameter>();
            RelatedToQuerySearchParameter relatedToQuerySearchParameter =
                new RelatedToQuerySearchParameter();
            relatedToQuerySearchParameter.queries = new String[] { keyword };
            searchParameters.Add(relatedToQuerySearchParameter);

            LanguageSearchParameter languageParameter = new LanguageSearchParameter();
            Language english = new Language();
            english.id = 1000;
            languageParameter.languages = new Language[] { english };
            searchParameters.Add(languageParameter);
            NetworkSetting networkSetting = new NetworkSetting();
            networkSetting.targetContentNetwork = false;
            networkSetting.targetGoogleSearch = true;
            networkSetting.targetPartnerSearchNetwork = false;
            networkSetting.targetSearchNetwork = false;
            NetworkSearchParameter networkSearchParameter = new NetworkSearchParameter() { networkSetting = networkSetting };
            searchParameters.Add(networkSearchParameter);
            selector.searchParameters = searchParameters.ToArray();
            Paging paging = Paging.Default;
            selector.paging = paging;
            TargetingIdeaPage page = new TargetingIdeaPage();
            try
            {
                do
                {
                    page = targetingIdeaService.get(selector); // gives error on this line
                    if (page.entries != null && page.entries.Length > 0)
                    {
                        foreach (TargetingIdea targetingIdea in page.entries)
                        {
                            Dictionary<AttributeType, Google.Api.Ads.AdWords.v201710.Attribute> ideas =
                                targetingIdea.data.ToDict();
                            long averageMonthlySearches = (ideas[AttributeType.SEARCH_VOLUME] as LongAttribute).value;

                            string keywordRes = (ideas[AttributeType.KEYWORD_TEXT] as StringAttribute).value;
                            Money averageCpc = (ideas[AttributeType.AVERAGE_CPC] as MoneyAttribute).value;
                            double competition = (ideas[AttributeType.COMPETITION] as DoubleAttribute).value;
                        }
                    }
                    selector.paging.IncreaseOffset();
                } while (selector.paging.startIndex < page.totalNumEntries);
                Console.WriteLine("Number of related keywords found: {0}", page.totalNumEntries);
            }
            catch (AdWordsException e)
            {
                throw new System.ApplicationException("Failed to retrieve related keywords.", e);
            }
        }

请帮助我的代码出错或如何实现功能。 谢谢＆amp;的问候，