Google API consent screen not showing up on after publishing to server

Question

I am working with the Google Provisioning API. I have used Web Application type project from Google developer console. I have used Diamto blog and samples and it works perfectly on my local with all options like FileStore, Custom File Store, Service Account etc but when I uploaded on server user consent screen just doesn't pops up with any options like FileStore, Custom File Store. I spent days to figure out problem and solutions but nothing has worked for me so far.

my configuration

1. My server configuration is windows server 2008 datacenter r2,.net 4.5,IIS 7.5.
2. Service account works perfectly but I need to do it by Consent screen so Web Application type of project.
3. I have used google .net client library with version 1.9.2.27817.
4. I am just highlighting main code where it gets stuck and rest is same as per Diamto post and github examples.

Let me know if you need more info.

Code

public static DirectoryService AuthenticateOauth(string clientId, string clientSecret, string userName, IDataStore datastore)
{
    string[] scopes = new string[] {DirectoryService.Scope.AdminDirectoryUser };    

            try
            {
                // here is where we Request the user to give us access, or use the Refresh Token that was previously stored in %AppData%
                UserCredential credential = GoogleWebAuthorizationBroker.AuthorizeAsync(new ClientSecrets { ClientId = clientId, ClientSecret = clientSecret }
                                                                                             , scopes
                                                                                             , userName
                                                                                             , CancellationToken.None
                                                                                             , datastore).Result; // at this point it calls getasynch method for custom datasource

                DirectoryService service = new DirectoryService(new BaseClientService.Initializer()
                {
                    HttpClientInitializer = credential,
                    ApplicationName = "GoogleProv",
                });
                return service;
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex.InnerException);
                return null;

            }

        }
                {
                    HttpClientInitializer = credential,
                    ApplicationName = "GoogleProv",
                });
                return service;
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex.InnerException);
                return null;

            }

        }


  ///<summary>
        // Returns the stored value for the given key or <c>null</c> if the matching file (<see cref="GenerateStoredKey"/>
        // in <see cref="FolderPath"/> doesn't exist.
        // </summary>
        // <typeparam name="T">The type to retrieve</typeparam>
        // <param name="key">The key to retrieve from the data store</param>
        // <returns>The stored object</returns>




        public Task<T> GetAsync<T>(string key)
        {
            //Key is the user string sent with AuthorizeAsync
            if (string.IsNullOrEmpty(key))
            {
                throw new ArgumentException("Key MUST have a value");
            }
            TaskCompletionSource<T> tcs = new TaskCompletionSource<T>();


            // Note: create a method for opening the connection.
            SqlConnection myConnection = new SqlConnection(myconn);
            myConnection.Open();

            // Try and find the Row in the DB.
            using (SqlCommand command = new SqlCommand("select RefreshToken from GoogleUser where UserName = @username;", myConnection))
            {
                command.Parameters.AddWithValue("@username", key);

                string RefreshToken = null;
                SqlDataReader myReader = command.ExecuteReader();
                while (myReader.Read())
                {
                    RefreshToken = myReader["RefreshToken"].ToString();
                }

                if (RefreshToken == null )
                {
                    // we don't have a record so we request it of the user.
                    tcs.SetResult(default(T)); // it comes here
                }
                else
                {

                    try
                    {
                        // we have it we use that.
                        tcs.SetResult(NewtonsoftJsonSerializer.Instance.Deserialize<T>(RefreshToken));
                    }
                    catch (Exception ex)
                    {
                        tcs.SetException(ex);
                    }

                }
            }

            return tcs.Task; // it comes here and than gets hang forever
        }

Any of your help is highly appreciated.