Why BoundService is null?

I'm really new at Android and try to create simple service. I checked an tried to Android Documentation

but i cannot start service. Service always null.Program is not calling boundServiceConnection function

Here my code Service code

class BoundService : Service() {
  private val localBinder: IBinder = MyBinder()
  override fun onBind(intent: Intent): IBinder? {
      return localBinder
  }

  fun randomGenerator(): Int {
      val randomNumber = Random()
      return randomNumber.nextInt()
  }

  inner class MyBinder : Binder() {
      fun getService(): BoundService = this@BoundService
  }
}

Here is my main activity

var boundService: BoundService? = null
var isBound = false
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
}

override fun onStart() {
    super.onStart()
    Intent(this, BoundService::class.java).also { intent ->
        bindService(intent, boundServiceConnection, Context.BIND_AUTO_CREATE)
    }
}

fun onButtonClick(v: View) {
    if (isBound) {
        val num: Int = boundService!!.randomGenerator()
        Toast.makeText(this, "number: $num", Toast.LENGTH_LONG).show()
    }
}

override fun onStop() {
    super.onStop()
    if (isBound) {
        unbindService(boundServiceConnection)
        isBound = false
    }
}

private val boundServiceConnection: ServiceConnection = object : ServiceConnection {
    override fun onServiceConnected(name: ComponentName, service: IBinder) {
        val binderBridge = service as MyBinder
        boundService = binderBridge.getService()
        isBound = true
    }

    override fun onServiceDisconnected(name: ComponentName) {
        isBound = false
        boundService = null
    }
}

With regard to the service component of your app, it should be registered in your application manifest.

The android guide on bound services seems to not provide any information on the required (and assumed missing) manifest entry as it was covered in the service overview.