Dynamic image scroll problem!

I was recently trying to create a portfolio page on my flash site. I used the tutorial on loading XML images to do so, (kirupa.com - Introduction to XML in Flash: Example: Portfolio) but I ran into a problem when I had too many thumbs to display on screen all at once. I created scroll buttons with an animation containing the dynamically loaded thumbs, however, when i scroll too far in any direction, all the images disappear! Is there any simple way to scroll dynamic images. (i have unique buttons and want it to continue scrolling when the user holds down the button) using a _x+=5 etc will not work currently because it wont continue to scroll, only the use of playing or doing previous frame –

onClipEvent (enterFrame) {
    if (_global.scroll_left == true) {
        _root.portfolio.scroll_out.prevFrame();
    } else if (_global.scroll_right == true) {
        _root.portfolio.scroll_out.nextFrame();
    }
}

will allow for a continuous scrolling of the images. but why do the images keep disappearing! I can give the fla file if anyone thinks they can help. Thanks!!