Transitions between movieclips in a container

My buttons are inside movieclips. Each button attaches another movieclip from the library into a container. Everytime I try the swf by pressing any button, it attaches perfectly to the container. The problem is that once a movieclip is attached, if I press another button, the new movieclip does not substitute the previous one.

Furthermore, I am also trying to have a nice transition between movieclips as per this tutorial:

The only difference is that this tutorial is for external swf and in my example, all the movieclips are already in the library.

Please help me. Here is the actions I have for the on release state:

on (release) {
if (_root.currMovie == undefined) {
_root.currMovie = “contact”;
_root.container.attachMovie(“contact”, “contact”, 1);
} else if (_root.currMovie != “contact”)
if (_root.container._currentframe >=
_root.container.midframe) {
_root.currMovie = “contact”;;