Image, or swf cacheing

Hi all

I am hoping someone can clear something up for me,

if i create an empty movieclip, then i load and image into it, then when clicking on a next button it loads the next image over that 1 and then again on the next button it loads the new image over that 1, is it supposed to cache the previous images that have already loaded? so if you click a previous button it doesn’t have to reload that image.

What is the best way to do that? i even tried creating new empty movieclips for each image that i want to load but for some reason if you cycle through the images you have to reload the image again and again.

Anyone know what the problem might be?

thanks