Bitmapdata transparent pixels

programming flash
1

Hey Kirupians

Im playing with some bitmapdata in flash, and Im really trying to wrap my head around it, but apparently my head is not big enough.

I have this code, that I would assume drew a 200x200 white rectangle, and then drew a 20x20 transparent cube inside. Instead it draws a black cube, inside the white cube.


var bmd:BitmapData = new BitmapData(200, 200, true, 0xFFFFFFFF);
var bitmap:Bitmap = new Bitmap(bmd);
addChild(bitmap);

for(var k:int=0; k<20; k++){
    for(var l:int=0; l<20; l++){
        bmd.setPixel(k, l, 0x00000000);
    }
}

What am I doing wrong?