Unable to save firebase firestore with kotlin android

Question

Now I'm running the firebase firestore example code.

Then failed to save and tried debugging using the println() function.

The debug results are output 1, 2, 3, 8.

The db.collection ("users") part is not running.

val firebaseTest:Button = findViewById(R.id.firebaseTest)
        firebaseTest.setOnClickListener {
            println(1)
            val db = Firebase.firestore
            println(2)
            // Create a new user with a first and last name
            val user = hashMapOf(
                "first" to "Ada",
                "last" to "Lovelace",
                "born" to 1815
            )

            println(3)
// Add a new document with a generated ID
            db.collection("users")
                .add(user)
                .addOnSuccessListener { documentReference ->
                    println(4)
                    Toast.makeText(this@LoginActivity, "success.", Toast.LENGTH_SHORT).show()
                    println(5)
                }
                .addOnFailureListener { e ->
                    println(6)
                    Toast.makeText(this@LoginActivity, "faild", Toast.LENGTH_SHORT).show()
                    println(7)
                }
            println(8)
        }