Fade in out

1

I am studying a actionscript book at the moment and i am trying out some stuff myself but got a little problem.

I wanted to make 2 movieclips that contain a motion tween that zooms in and then zooms out.

I wanted 2 buttons to control those movieclips.

when i would click on button one, mc1 would zoom in.
when i would click on button two then, mc1 zooms out first and then mc2 starts the zoom in.

the mc’s contain 20 frames, both a tween from 1 to 11 and then a tween from 11 to 20. with stop signs on frame 1 and 2 and a framelabel called start on frame 1. both mc’s are copy’s of eithother only the instance names are different.

this is the script that i placed on frame on of scene 1, please let me know what i am doing wrong.

mc1.stop();
mc2.stop();

btn1.onPress = function() {
    if (mc2="start"){
    mc1.play();
    }
} else {
    mc2.play();
}
btn2.onPress = function() {
    if (mc1="start"){
    mc1.play();
    }
} else {
    mc1.play();
}