Firebase Database Rules indexOn FIREBASE WARNING: Using an unspecified index

Question

Firstly, I received this warning

FIREBASE WARNING: Using an unspecified index. Consider adding ".indexOn": "id" at / data / places / tr to your security rules for better performance

After I changed the firebase rules.

{
  "rules": {
    ".read": "true",
    ".write": "true",
   "data": {
    "places": {
      "tr": {
        ".indexOn": "id"
      }
    }
   }
  }
}

Now I have no warning, but the code is not working.