Canvas won't scroll content, but scrollbar appears?

Question

Hello, i've tried porting this at actionscript.org with no
luck.
I have a class that extends canvas and i populate the object
like so:
for each (var group:XML in dataProvider.group) {
card
= new CardComponent();
card.x = this.x + (offset_x * i);
card
.y = this.y + (offset_y * i);
card.z = z_depth;
this.addChild(card
i++;
the scrollbar will appear when the cards total width exceeds
the boundaries, but the scrollbar doesn't scroll the content (the
cards) when dragged back and forth. Although the scrollbar does
appear to adjust it's size correctly proportionate to the content.
Is there additional code i need to add for the scroll functionality
to move the content? Thank you in advance -b

Answer 1

Thanks kglad
but that didn't seem to help, though to be honest, I'm not absolutely sure how to use the 'invalidate()'
I've attached the code below - hopefully you'll spot this newbies error!
I thought I'd add 2 buttons that simply changed the source between a .swf and a .jpg.  If I load the .swf, no scrollbars, if I load the .jpg, then scrollbars appear??
import flash.events.Event;
stop();
stage.invalidate();
Gigs.verticalLineScrollSize = 10;
Gigs.verticalPageScrollSize = 10;
Gigs.horizontalLineScrollSize= 20;
bGigs.addEventListener(MouseEvent.CLICK,LoadGig);
function LoadGig(evt:Event):void{
      Gigs.source = "Gigs.swf";
bPoster.addEventListener(MouseEvent.CLICK,LoadPoster);
function LoadPoster(evt:Event):void{
      Gigs.source = "SyntronixPoster.jpg";
Many thanks for your help so far