Hi I'm not able to change the background color I'm getting a runtime error saying java.lang.NullPointerException

public class MainActivity extends ActionBarActivity {
    Random generator = new Random();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final TextView factLabel = (TextView) findViewById(R.id.factTextView);
        final RelativeLayout relative = (RelativeLayout)findViewById(R.id.relativeLayout);
        Button nextFact = (Button) findViewById(R.id.nextFactButton);

        View.OnClickListener listener = new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                factLabel.setText(FactBook.getFact());
                relative.setBackgroundColor(Color.RED);
            }
        };

        nextFact.setOnClickListener(listener);
    }
}

02-14 19:09:03.541  32629-32629/com.example.kumar.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.kumar.myapplication, PID: 32629
    java.lang.NullPointerException
            at com.example.kumar.myapplication.MainActivity$1.onClick(MainActivity.java:34)
            at android.view.View.performClick(View.java:4463)
            at android.view.View$PerformClick.run(View.java:18789)
            at android.os.Handler.handleCallback(Handler.java:808)
            at android.os.Handler.dispatchMessage(Handler.java:103)
            at android.os.Looper.loop(Looper.java:193)
            at android.app.ActivityThread.main(ActivityThread.java:5299)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:825)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641)
            at dalvik.system.NativeStart.main(Native Method)