Unable to Bind server side data if I have bind list locally.

Question

I have developed a chat aaplication and after click on send button message thake 3-4 second for update so I have try to bind list from local database, But After that my server data doesn't update on list.

 

var todoItem = new Chat { UserMessage = _etMessage.Text, UserName = User.UserName, Key = rm.Key };

await App.Database.SaveItemAsyncChat(todoItem);

_lstChat.BindingContext = await App.Database.GetItemsAsyncc();

var chatOBJ = new Chat { UserMessage = _etMessage.Text, UserName = User.UserName };

_etMessage.Text = "";

await db.saveMessage(chatOBJ, rm.Key);

// db.subChat(rm.Key);

var firebase = new FirebaseClient("https://hardwarechatxamarin.firebaseio.com/");

_lstChat.BindingContext = firebase

.Child("ChatApp/" + rm.Key + "/Message")

.AsObservable();