useSelector doesn't work in react redux app

I am creating a counter application using react and redux.

In the counterSlice.js file, I included this line:
export const selectCount = (state) => state.count;

And in the Counter.js file, I have included these lines:

import { changeValueBy, selectCount } from "./counterSlice";

const count = useSelector(selectCount);

But the value of count remains undefined.
My complete code is here.
Please tell me what I’m doing wrong.

>Solution :

You missed out to create a store and wrap the app with its Provider as following:

import { Counter } from "./features/counter/Counter";
import { Provider } from "react-redux";
import { createStore } from "redux";
import counter from "./features/counter/counterSlice";

const store = createStore(counter);

function App() {
  return (
    <Provider store={store}>
       <Counter />
    </Provider>
  );
}

export default App;

BTW, I fixed your codesanbox here