JMF Audio Player

Question

I was creating a Audio Player in Java using JMF API but i am stucked in creating volume controls (setMute() is throwing Exception) and integrating them with JSlider. Heres the code for Mute Functionality:

public void volume()
{
     if(ismute)
     {   
         gc.setMute(false); *//GainControls gc*
         volbutton.setIcon(new ImageIcon("Volume.png"));
         ismute = false;
     }
     else
     {
         gc.setMute(true);
         volbutton.setIcon(new ImageIcon("Mute.png"));
         ismute = true;
     }
}