Java Sound API and JSliders

[Eric Hensel]

So I've been reading through the Java Sound API, which isn't necessarily a walk in the park, trying to find out how to get control of my PC's main Speakers.
I'm currently writing a program that I want to be able to control my PC's main audio output through a JSlider. For example, if I was playing a song on iTunes
I would like to be able to adjust the volume from my GUI.

I've looked through these two articles in the Java Sound documents: http://docs.oracle.com/javase/tutorial/sound/accessing.html
http://docs.oracle.com/javase/tutorial/sound/controls.html
And I've also been using this thread to help me find the specific port for my speaker on my PC: http://www.coderanch.com/t/492931/java/java/Adjusting-master-volume-Windows-XP

I've been using a test program with just one JSlider to try to get control of my speakers. Under the slider's ChangeListener method I have the following code:

Port SPEAKER;
        FloatControl volCtrl;
        try {
          Mixer mixer = AudioSystem.getMixer(null);
          SPEAKER = (Port)mixer.getLine(Port.Info.SPEAKER);
          SPEAKER.open();
          volCtrl = (FloatControl) SPEAKER.getControl(

            FloatControl.Type.VOLUME);

        } catch (Exception e) {
        System.out.println("Failed trying to find LINE_IN"
            + " VOLUME control: exception = " + e);
        }

Whenever I move the slider it prints out the error Exception message "Failed trying to find...". Why isn't it letting me obtain the volCtrl on my main output speakers?
How can I fix this code to get control of my SPEAKER?