Why i get error imageView1 cannot be resolved or is not field?

Question

i get error imageView1 cannot be resolved or is not field. What i have to do? I don't understand. All the code is correct.

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.Menu;
import android.widget.ImageView;

public class MainActivity extends Activity {

    private ImageView iv;
    private Bitmap bitmap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv = (ImageView) findViewById(R.id.imageView1);
        bitmap = getBitmapFromURL("http://icons.iconarchive.com/icons/crountch/one-piece-jolly-roger/72/Luffys-flag-2-icon.png");
        iv.setImageBitmap(bitmap);

    }