How to stop or pause Pandora and Spotify

I have an application that has the function of launching an application, Pandora station or shortcut. Everything works perfectly. Later I want to stop the application that I started. This works for most things except Pandora and Spotify, which don't always close. Sometimes they do, but not always. This seems to be related to the current state of the user interface. For example, it works great when I show Pandora or the home screen is displayed. When Home Dock or Car Mode are active, it does not work. Here you can see all the source code: http://code.google.com/p/a2dpvolume/ service.java is a file with this functionality.

Here is the part of this code that tries to stop the music playing and then stops the application.

if (bt2.hasIntent()) {
        // if music is playing, pause it
        if (am2.isMusicActive()) {
            // first pause the music so it removes the notify icon
            Intent i = new Intent("com.android.music.musicservicecommand");
            i.putExtra("command", "pause");
            sendBroadcast(i);
            // for more stubborn players, try this too...
            Intent downIntent2 = new Intent(Intent.ACTION_MEDIA_BUTTON, null);
            KeyEvent downEvent2 = new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_STOP);
            downIntent2.putExtra(Intent.EXTRA_KEY_EVENT, downEvent2);
            sendOrderedBroadcast(downIntent2, null);
        }

        // if we opened a package for this device, try to close it now
        if (bt2.getPname().length() > 3 && bt2.isAppkill()) {
            // also open the home screen to make music app revert to
            // background
            Intent startMain = new Intent(Intent.ACTION_MAIN);
            startMain.addCategory(Intent.CATEGORY_HOME);
            startMain.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(startMain);
            // now we can kill the app is asked to

            final String kpackage = bt2.getPname();
            CountDownTimer killTimer = new CountDownTimer(6000, 3000) {
                @Override
                public void onFinish() {
                    try {
                        stopApp(kpackage);
                    } catch (Exception e) {
                        e.printStackTrace();
                        Log.e(LOG_TAG, "Error " + e.getMessage());
                    }
                }

                @Override
                public void onTick(long arg0) {

                    if (am2.isMusicActive()) {

                        // for more stubborn players, try this too...
                        Intent downIntent2 = new Intent(Intent.ACTION_MEDIA_BUTTON, null);
                        KeyEvent downEvent2 = new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_STOP);
                        downIntent2.putExtra(Intent.EXTRA_KEY_EVENT, downEvent2);
                        sendOrderedBroadcast(downIntent2, null);
                    }

                    try {
                        stopApp(kpackage);
                    } catch (Exception e) {
                        e.printStackTrace();
                        Log.e(LOG_TAG, "Error " + e.getMessage());
                    }
                }
            };
            killTimer.start();

        }
    }

Here is the stopApp () function.

protected void stopApp(String packageName) {
    Intent mIntent = getPackageManager().getLaunchIntentForPackage(
            packageName);
    if (mIntent != null) {
        try {

            ActivityManager act1 = (ActivityManager) this
                    .getSystemService(ACTIVITY_SERVICE);
            // act1.restartPackage(packageName);
            act1.killBackgroundProcesses(packageName);
            List<ActivityManager.RunningAppProcessInfo> processes;
            processes = act1.getRunningAppProcesses();
            for (ActivityManager.RunningAppProcessInfo info : processes) {
                for (int i = 0; i < info.pkgList.length; i++) {
                    if (info.pkgList[i].contains(packageName)) {
                        android.os.Process.killProcess(info.pid);
                    }
                }
            }
        } catch (ActivityNotFoundException err) {
            err.printStackTrace();
            Toast t = Toast.makeText(getApplicationContext(),
                    R.string.app_not_found, Toast.LENGTH_SHORT);
            if (notify)
                t.show();
        }

    }
}

Is anyone else facing this issue? How can I reliably stop a running application? I need to pause first and put it in the background. This is the problem I am having. It works for most situations, but not for everyone. In some cases, Pandora and Spotify will not respond to the key event being sent, and they just keep playing. This keeps the notification icon active and makes the application a priority, so I cannot stop it.