Beginner needs help with alpha fade on loaded images

It has been years since I have used flash so I am probably a beginner again. I have just got CS3 but most of what I remember I think is action script 1.

I have a website that I want to make the images load from external into swf file. I want to then control the alpha with the rollover. I got so far but… alpha works only if jpg is inside. when I have it outside it just flashes on and off on load. I know this is basic but a push in the right direction is going to help me grately… Please see code below.

I need to make the my_mc to load from outside then fade in. After which I have the rollover fade in/out code below…

Button.prototype.fadeIn = MovieClip.prototype.fadeIn = function () {
this.onEnterFrame = function () {
if (this._alpha<100) {
this._alpha += 10; }
else {
delete this.onEnterFrame;
}
};
};

Button.prototype.fadeOut = MovieClip.prototype.fadeOut = function () {
this.onEnterFrame = function () {
if (this._alpha>0) {
this._alpha -= 10; }
else {
delete this.onEnterFrame;
}
};
};
my_mc.onRollOver = fadeIn;
my_mc.onRollOut = fadeOut;

If you can help me thankyou!