App crashes when requesting permission

I'm using this code to request SMS permission before running the method SendSMS(string 1, string 2);but my app crashes before permission request takes place.What's missing?

 final private int REQUEST_CODE = 101;private void SendCreditSMS() {    if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.SEND_SMS)            != PackageManager.PERMISSION_GRANTED) {        ActivityCompat.requestPermissions(MainActivity.this,                new String[]{Manifest.permission.SEND_SMS}, REQUEST_CODE);    } else {        SendSMS("181", "رصيد");    }}