How can I sum multuple childs in FireBase

I have a problem with my code.. I can't Sum from multiple Childs in Fire Base...

I try use this Code

reference = FirebaseDatabase.getInstance().getReference("Finance").child(auth.getUid()).child("Data");
    reference.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    dFinance = new ArrayList<>();
                    int pemasukan = 0;

                    int total = 0;
                    for(DataSnapshot ds : dataSnapshot.getChildren()) {
                        int value =  Integer.valueOf(ds.child("pemasukan").getValue(String.class));
                        total =+ value;
                    }
                    TextView dt_pemasukan = root.findViewById(R.id.dt_pemasukan);
                    dt_pemasukan.setText(total);
                }
                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

but the error shows

    2021-05-05 22:38:08.510 20308-20308/com.kuplay.storingdata E/lay.storingdat: Invalid ID 0x00000000.
2021-05-05 22:38:08.513 20308-20308/com.kuplay.storingdata D/AndroidRuntime: Shutting down VM
2021-05-05 22:38:08.530 20308-20308/com.kuplay.storingdata E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.kuplay.storingdata, PID: 20308
    android.content.res.Resources$NotFoundException: String resource ID #0x0
        at android.content.res.Resources.getText(Resources.java:490)
        at android.widget.TextView.setText(TextView.java:6504)
        at com.kuplay.storingdata.Fragment.data.DataFragment$2.onDataChange(DataFragment.java:96)
        at com.google.firebase.database.Query$1.onDataChange(Query.java:191)
        at com.google.firebase.database.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:75)
        at com.google.firebase.database.core.view.DataEvent.fire(DataEvent.java:63)
        at com.google.firebase.database.core.view.EventRaiser$1.run(EventRaiser.java:55)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:239)
        at android.app.ActivityThread.main(ActivityThread.java:8179)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:626)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1015)

I've tried many ways to solve this but the rerult is still same

this is my FireBase Data my FireBase Data