Android : Why does BUTTON.setEnabled(true); lead to a nullpointer exception if BUTTON is not null?

I get

 Caused by: java.lang.NullPointerException
        at ente.testen.Testen.onCreate(Testen.java:210)

pointing to

            btnAendern.setEnabled(true);

in

    final Button btnAendern = (Button) findViewById(R.id.btnAendern);

    final Intent absicht = getIntent();
        if (absicht == null)
            btnAendern.setEnabled(false);
        else
            btnAendern.setEnabled(true);

Android Studio 1.0 does not show R.id.btnAendern underlined, so it does find it. Using

    if (btnAendern != null) {
        if (absicht == null)
            btnAendern.setEnabled(false);
        else
            btnAendern.setEnabled(true);
    }

Still let's Android point to btnAendern.setEnabled(true);.

What could be the cause for this?