Why is code to get center of image not working?

Question

Hey there. I have am trying to establish the center of the imags that load so that I can put them in the center of the stage. I am doing this as each image is a different size.
Here is the code i have gotten to work before but its not working now and I have been searching to find what I have done wrong with no luck. : (
Would you look it over and maybe you will see what I am doing wrong?
public function placePicture(e:Event = null):void {
     rawImage = imageData.image[imgNum].imageURL;
     lastImageIndex = imageData.*.length() - 1;
     imageLoader = new Loader;
     imageHolder = new Sprite;
     imageLoader.load(new URLRequest(rawImage));
     imageLoader.x -= imageLoader.width/2; //this should set the image to the center no?
     imageLoader.y -= imageLoader.height/2;
     imageHolder.x = 640; //this is the center of the stage
     imageHolder.y = 100;
     imageHolder.addChild(imageLoader);
     masterHolder.addChild(imageHolder);    
The result when I publish is the picture comes on stage but the top left corner goes to 640 instead of the center of the image going to 640.
I tried several variations of this all with the same result:
imageLoader.x = -1*imageLoader.width/2;
I tried using setRegistrationPoint with the following tutorial: http://flashscript.ca/set-registration-as3.php
and I tried doing all of the above by inserting the loader into a sprite and then applying the code to the sprite and then adding that sprite to another sprite and putting that at 640 and not inserting it in another sprite and trying to straight up put the existing sprite at 640 (hopefully that all makes sense). And I have tried to put it to width/3 and nothing different happens.
If you have any other ideas or can see what I am doing wrong I would really be gratefull for some tips! : )
Thanks for any help!
oh, and I am getting no errors on this.

Answer 1

the image's width and height are not available until loading is complete.  ie, use a complete listener/listener function.