Web API在LinqToTwitter查询后没有返回响应

我有一个问题，在通过LinqToTwitter库从web api控制器中查询twitter后，我的代码停止执行，web api动作未能返回响应。我怀疑web api和linqToTwitter之间可能存在某种冲突，但我在这里完全没有头绪。下面是代码:

// This class is my wrapper for linqToTwitter
public class Twitter
{
// FIELDS
    private readonly MvcAuthorizer _auth;
    // PROPERTIES
    public TwitterContext Twit
    {
        get
        {
            return new TwitterContext(_auth);
        }
    }
public Twitter()
    {
        // all keys
        var cKey = ConfigurationManager.AppSettings[
            "twitConsumerKey"];
        var cSecKey = ConfigurationManager.AppSettings[
            "twitConsumerSecret"];
        var oToken = AuthTool.getUserTwitterTokens().token;
        var oTokenSecc = AuthTool.getUserTwitterTokens()
            .tokenSecret;
        ICredentialStore cred = new InMemoryCredentialStore();
        cred.ConsumerKey = cKey; 
        cred.ConsumerSecret = cSecKey;
        cred.OAuthToken = oToken;
        cred.OAuthTokenSecret = oTokenSecc;
        // get auth
        _auth = new MvcAuthorizer()
                {
                    CredentialStore = cred
                };
    }
// This is the specific method called from within the web api action
public string RetrieveTwitterId(string twitName)
{
    // this statement executes a successful linqToTwitter query as verified with fiddler 
    // but doesn't return anything to the user variable. The rest of the code does not execute.
    var user = Twit.User.SingleOrDefault
        (x => x.Type == UserType.Show &&
               x.ScreenName == twitName);
    if(user != null)
    {
       return user.UserID.ToString("F0");
    }
    return null;
 }
 }

这是正在被调用的web api操作:

[HttpPost]
public HttpResponseMessage CreateNewInterview(Model.NewInterview interview)
    {
        // find twitter Id
        var twitterId = new Twitter().RetrieveTwitterId(interview.SubjectTwitterName);// nothing is returned here and nothing executes below

        // assign model
        var model = new NewInterview
            (interview.Title, twitterId, DateTime.Now, interview.PublicQuestions,   interview.Category);
        // create the new interview
        Admin.createInterview(model);
        // create response
        return Request.CreateResponse(HttpStatusCode.OK);
    }

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.Entity;// <-- Had to remove this one!!!
using System.Linq;
using System.Threading.Tasks;
using System.Web;
using System.Web.Mvc;
using LinqToTwitter;
using LinqToTwitter.Security;
using TwitterTools;