Scripting issues

K im having problems witht his thing.
i have buttons,that control the yscale of a movieclip, i was succesful with one, but when i make more, it scales all the clips?

button code:
on (rollOver) {
_root.targYscale =400;
}
on (rollOut) {
_root.targYscale = 0;
}

movieclip code:
onClipEvent (load) {
_root.targYscale = 0;
}
onClipEvent (enterFrame) {
//cXscale = this._xscale;
cYscale = this._yscale;
//difXscale = cXscale-_root.targXscale;
difYscale = cYscale-_root.targYscale;
setProperty(this, _xscale, cXscale-(difXscale/5));
setProperty(this, _yscale, cYscale-(difYscale/5));
}

can any one help out?