onEnterFrame looping problem

programming flash
1

Hey guys,
So I have this code below.

function myfunction():Void {
	for (i = 0; i < 100; i++) {
		_root.attachMovie('platform','platform_' + i,i,{_x:275 + i * 100, _y:200});
	}
}
myfunction();
_root['platform_' + i].onEnterFrame = function():Void  {
	_x -= 5;
};

The code generates 5 platforms movieclips and is also placing them on 275x and 200y. There is a space of 100 pixels between each of them. I want to give all of these platforms an action to do, like _x -= 5; but it
simply doesn’t work with what I’ve written.

Could anyone tell me what I’m doing wrong?

Thanks!