Movement Using ActionScript

1

I have a movie clip that I would like to slide to the right or left depending on which button the user clicks. When I test the movie and click on the buttons, the target movie clip only moves one pixel. I want it to slide into place. What am I doing wrong?

leftBtn.onRelease = function() {
if (_root.info_mc._x>490) {
speed = -5;
_root.info_mc._x += speed;
}
else {
_root.info_mc._x = 490;
}
};

rightBtn.onRelease = function() {
if (_root.info_mc._x<590) {
speed = 5;
_root.info_mc._x += speed;
}
else {
_root.info_mc_x = 590;
}
};

Thank you in advance for your help.