Help with depth on flash 8

hi,

im having a problem with the depth of loading objects (movieclips)

i have 3 buttons on the stage (or within a movieclip on stage), and 3 objects (mc’s) in the library,
now - How do I set the depth of an objects?

i used on each button :

[COLOR=Black]on(release){
var t:MovieClip = this.attachMovie(“Blue”,pop1,this.getNextHighestDepth());
t._x = 0;
t._y = 134.5;
}[/COLOR]

and still the objects stay the same, i want them to go on top of the other 2…

any one can help?