How to change image?

Hello, I am learning Java and I have a question :)

In the panorama applet I draw an image into the screen. Image is in
variable "pano", which is loaded on the beginning. If I click on the
right place on the image, method show_window from applet "target"
should load new image into variable "pano" and the whole picture should
change. But in my case it does not change. Do you know what shoult I do
to change and display image in the variable "pano"?

I hope it is clear enough :)

public class panorama extends Applet
{
    public static panorama selfRef = null;
    public Image pano;

    public void init()
    {
    selfRef = this;
        String s1 = getParameter("panorama");
    loadImage(s1);
    }

    public void loadImage(String mainPicture)
    {
    pano = getImage(getCodeBase(), mainPicture);
    }

    public void paint(Graphics g)
    {
        width = pano.getWidth(this);
        /*
        ...
        */
    }
}

public class target extends JApplet
{
    String file;

    public void show_window(Applet applet)
    {
    if (file.equals("Train.jpg"))
    {
        panorama panoramaApplet = null;
        panoramaApplet = panorama.selfRef;
        panoramaApplet.loadImage("Train.jpg");
    }
    }
}