Firebase.database.DatabaseException: Expected a Map while deserializing, but got a class java.lang.String

I'm trying to use Firebase Database but I get that exception (in the title). First I wrote under onDataChange: Map map = dataSnapshot.getValue(Map.class); but then they asked me to use a generictypeindicator, which I did. However, I now get this new exception. How do I fix this?

Here are some important lines of code

    //accessing the firebase database
    database=FirebaseDatabase.getInstance();
    //creates a database references
    databaseRef1=database.getReference().child("Ben_Ptolemy");
    databaseRef2=database.getReference().child("Ptolemy_Ben");

 sendButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String messageText = messageArea.getText().toString();

            if(!messageText.equals("")){
                Map<String, String> map = new HashMap<String, String>();
                map.put("message", messageText);
                map.put("user", "Ben");
                databaseRef1.push().setValue(map);
                databaseRef2.push().setValue(map);
                messageArea.setText("");
            }
        }
    });

    databaseRef1.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Log.d("firebase received", "true");


            GenericTypeIndicator<Map<String, String>> genericTypeIndicator = new GenericTypeIndicator<Map<String, String>>() {};
            Map<String, String> map = dataSnapshot.getValue(genericTypeIndicator );
            String message = map.get("message").toString();
            String userName = map.get("user").toString();

            if(userName.equals("Ben")){
                addMessageBox("You:-\n" + message, 1);
            }
            else{
                addMessageBox("Ptolemy" + ":-\n" + message, 2);
            }
        }

Ok, finally got this to work. I used addChildEventListener instead of addValueEventListener and replaced Map map = dataSnapshot.getValue(Map.class); with Map<String, Object> map = (Map<String, Object>) dataSnapshot.getValue(); and everything worked.