Invalid API Key in OpenWeatherMap (Error 401)

I'm trying to make an API call to OpenWeatherMap. When I execute flutter run in the terminal, the response.statusCode prints 401 which is code for Invalid API Key, although I have generated the API Key in an appropriate way and it is active and copied correctly.

const APIKey = '69f9afe03f52ef5c83887fc86dd79d99';

  void getData() async {
    http.Response response = await http.get(Uri.parse('https://api.openweathermap.org/data/3.0/onecall?lat=$latitude&lon=$longitude&appid=$APIKey'));
    if (response.statusCode == 200) {
      String data = response.body;
      var decodedData = jsonDecode(data);
      print(decodedData);
    } else {
      print(
        response.statusCode,
      );
    }
  }

Geolocator package for Flutter was used to assign the Latitude and Longitude. How can the 401 Error be rectified?

checkout Using OpenWeatherMap API gives 401 error here you will find some reasons why your apikey is not working. also, it takes 2 hours for key activation.