在使用Microsoft bot框架的Microsoft团队中显示欢迎消息

我已使用以下代码向用户显示欢迎消息.

I have used below code for showing a welcome message to user.

private Activity HandleSystemMessage(Activity message)
        {
            if (message.Type == ActivityTypes.DeleteUserData)
            {
                // Implement user deletion here
                // If we handle user deletion, return a real message
            }
            else if (message.Type == ActivityTypes.ConversationUpdate)
            {
                string replyMessage = string.Empty;
                replyMessage = Responses.Greeting;
                return message.CreateReply(replyMessage);
            }
            else if (message.Type == ActivityTypes.ContactRelationUpdate)
            {
                // Handle add/remove from contact lists
                // Activity.From + Activity.Action represent what happened
            }
            else if (message.Type == ActivityTypes.Typing)
            {
                // Handle knowing tha the user is typing
            }
            else if (message.Type == ActivityTypes.Ping)
            {
            }
            return null;
        }

如果活动类型不是消息，则下面的方法用于调用HandleSystemMessage.

Below method is used to call HandleSystemMessage, if activity type is not message.

public async Task<HttpResponseMessage> Post([FromBody]Activity activity)
        {
            string reply = "";
            ConnectorClient connector = new ConnectorClient(new Uri(activity.ServiceUrl));
            if (activity.Type == ActivityTypes.Message)
            {
                    stLuis = await LuisHelper.ParseUserInput(activity.Text);

                    string userResponse = activity.Text.ToLower();

                    switch (stLuis.topScoringIntent.intent)
                    {
                        case "Greetings":
                            reply = Responses.Greeting;
                            break; 

                        case "None":
                            reply = Responses.None;
                            break;

                        default:
                            break;
                    }
                }

                if (reply != "")
                    await connector.Conversations.ReplyToActivityAsync(activity.CreateReply(reply));
            }
            else
            {
                var reply1 = HandleSystemMessage(activity);
                if (reply1 != null)
                    await connector.Conversations.ReplyToActivityAsync(reply1);
            }
            var response = Request.CreateResponse(HttpStatusCode.OK); 
            return response;
        }

此代码适用于Skype.但是，当我在Microsoft团队中添加相同的漫游器时，它不会显示欢迎消息.

This code works with Skype. But when I add same bot in Microsoft teams, it doesn't show a welcome message.