Swing/AWT/SWT :: JScrollPane Programmatic Scrolling

I have Implemented a user control / component that allows zooming in and out of a displayed BufferedImage, for discussion's sake, 3rd party libraries are excluded and everything must be from scratch.I have an image rendered on a JPanel, the JPanel is contained within a scrollbar.

Zooming inout etc works perfectly.The Scrollbars are rendered correctly on Zoom In and disappear when I zoom out.I want to add the functionality of focusing on a specific quarter of the displayed image via four dedicated buttons, each send an int (1-4) to a method, that controls the scrollbars.

public void zoomToQuarter(int i)
{
double width = (currentBufferedImage.getWidth()*2.2)+1;
double height = (currentBufferedImage.getHeight()*2.2)+1;
JScrollBar vertical = scrollPane.getVerticalScrollBar();
JScrollBar horizontal = scrollPane.getHorizontalScrollBar();
horizontal.setMaximum((int)width);
vertical.setMaximum((int)height);

[code]....

And resizes the image whilst scrolling the scrollbars accordingly,The method works as expected, and the scrollbars go to the desired location, But there's a catch:The first click on any of the above buttons does not work, but from the second click and on, everything works great!