In a forloop as assignen

I have a little question beqause I cant figure it out myself, its probably so simple, that I have to be verry embaressed …

On my stage I have 8 buttons, named “knop0”, “knop1”, “knop2”, etc till 8

for (var a:Number=0; a<9; a++) {
    this["knop"+a].addEventListener(MouseEvent.CLICK, leesMap, a);
}

function leesMap(welke:int):void {
    trace(welke);
}

But with this code, only knop0 does what I expect, the rest from the buttons does nothing.
I also tried root and stage (are there anymore options ?) but besides errors it gives me nothing, or less :slight_smile:

[SIZE=1]help ! :q:[/SIZE]