Simple movement problems

Hi,

I have a movie clip that i want to attach to the stage and then move…I can attach it but i cant get it to move…Here is the script i used. Any ideas? I have the code in a movie clip on the stage. I have also tried using…this._x += xmov but find that other things on the stage move along with the ball.

Quote:
onClipEvent (load) {
timeBetweenBalls = 2000;
nextBall = getTimer() + timeBetweenBalls;
score = 0;
numBalls = 0;
lastBall = 0
xmov = 5;
}

onClipEvent (enterFrame) {
// see if it is time for the next ball
if (getTimer() >= nextBall) {

// shorter wait next time
timeBetweenBalls -= 10;

//attach ball and then move it
attachMovie(“ball”, “ball”+lastBall, lastBall);
_root[“ball”+lastBall]._x += xmov;
}
}