Dynamicly created movieclip/sprite and .width property

I have a question on WHEN you can read the width of a dynamically created sprite.

I have a gallery package - the gallery.as file creates a thumbContainer (MovieClip) and adds each thumbnail (sprite) in a for loop, iterating through an array.

Within the for loop, i try to trace the width of the thumbContainer, but it always returns 0. What gives? I need the final width to make some calculations for the scrolling of the thumbnails to work.

I can get the final width using certain methods, such as returning the width on MOUSE_MOVE. I was able to get the width using the eventListener Event.ADDED, but that stopped working when loading images off my server instead of locally (wtf is that about?).

Can anyone give some clarification on dynamically created containers and their properties (specifically reading their width property) ?