Class extends movieclip

Hello,

I have a little prob here, maybe someone can help me…

in human.as:
class human extends MovieClip {
function onEnterFrame() {
_x += 10;
}
function human() {
attachMovie(“skin1”, “skin1”, 1);
}
}
in my fla:
Object.registerClass(skin1, human);
_root.attachMovie(“skin1”, “User1”, 1);

so i have an attached movieclip on _root now, i can see it but the onEnterFrame function doesn’t work. Why?? :dog: