Firebase连接在Kotlin上创建用户错误

ı尝试与kotlin的firebase创建用户。 但是我总是得到错误敬酒Theese是我的import：

import android.content.Intent import android.support.v7.app.AppCompatActivity import android.os.Bundle import android.text.TextUtils import android.view.View import android.widget.Toast import com.google.firebase.auth.FirebaseAuth import kotlinx.android.synthetic.main.activity_create_user.* 

这里剩下的我的代码类createUser：AppCompatActivity（）{private var fbsignup：FirebaseAuth = FirebaseAuth.getInstance（）

 override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_create_user) submitButton.setOnClickListener { val email = userSaveText.text.toString().trim() val password = passSaveText.text.toString().trim() if (TextUtils.isEmpty(email)) { Toast.makeText(this, "enter a mail ", Toast.LENGTH_SHORT).show() return@setOnClickListener } if (TextUtils.isEmpty(password)) { Toast.makeText(this, "enter password", Toast.LENGTH_SHORT).show() return@setOnClickListener } fbsignup.createUserWithEmailAndPassword(email, password).addOnCompleteListener { task -> if (task.isSuccessful) { Toast.makeText(this, "succesfully created account", Toast.LENGTH_SHORT).show() return@addOnCompleteListener } else { Toast.makeText(this, "errore!!", Toast.LENGTH_SHORT).show() return@addOnCompleteListener } }} } 

我应该做些什么？